1
|
Dreyfuss G. RNA-binding proteins in disease etiology: fragile X syndrome and spinal muscular atrophy. RNA (NEW YORK, N.Y.) 2025; 31:277-283. [PMID: 39694825 PMCID: PMC11874976 DOI: 10.1261/rna.080353.124] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/04/2024] [Accepted: 12/04/2024] [Indexed: 12/20/2024]
Abstract
All RNAs exist in complexes (RNPs) with RNA-binding proteins (RBPs). Studies in my lab since the 1980s have identified, sequenced and characterized the major pre-mRNA- and mRNA-RBPs (hnRNPs/mRNPs), revealing RNA-binding domains and common features of numerous RBPs and their central roles in posttranscriptional gene regulation. The first links between RBPs and RNPs to diseases emerged serendipitously for fragile X syndrome, as its gene (FMR1) encoded RBP (FMRP), and spinal muscular atrophy (SMA), caused by deficits in survival motor neurons (SMN). Discoveries of the SMN complex and its unanticipated function in RNP assembly, essential for spliceosomal snRNP biogenesis, advanced understanding of RNA biology and pathogenesis. I reflect on how these and other contributions (e.g., nucleocytoplasmic shuttling, telescripting) originated from curiosity-driven exploration and highly collaborative lab culture. The vast RNA and RBP assortments are beneficial, but increase complexity and chances of disorders, making the RNP sphere a rich source for future discoveries.
Collapse
Affiliation(s)
- Gideon Dreyfuss
- Department of Biochemistry and Biophysics, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania 19104, USA
| |
Collapse
|
2
|
Blatnik AJ, Sanjeev M, Slivka J, Pastore B, Embree CM, Tang W, Singh G, Burghes AHM. Sm-site containing mRNAs can accept Sm-rings and are downregulated in Spinal Muscular Atrophy. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.10.09.617433. [PMID: 39416143 PMCID: PMC11482833 DOI: 10.1101/2024.10.09.617433] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/19/2024]
Abstract
Sm-ring assembly is important for the biogenesis, stability, and function of uridine-rich small nuclear RNAs (U snRNAs) involved in pre-mRNA splicing and histone pre-mRNA processing. Sm-ring assembly is cytoplasmic and dependent upon the Sm-site sequence and structural motif, ATP, and Survival motor neuron (SMN) protein complex. While RNAs other than U snRNAs were previously shown to associate with Sm proteins, whether this association follows Sm-ring assembly requirements is unknown. We systematically identified Sm-sites within the human and mouse transcriptomes and assessed whether these sites can accept Sm-rings. In addition to snRNAs, Sm-sites are highly prevalent in the 3' untranslated regions of long messenger RNAs. RNA immunoprecipitation experiments confirm that Sm-site containing mRNAs associate with Sm proteins in the cytoplasm. In modified Sm-ring assembly assays, Sm-site containing RNAs, from either bulk polyadenylated RNAs or those transcribed in vitro , specifically associate with Sm proteins in an Sm-site and ATP-dependent manner. In cell and animal models of Spinal Muscular Atrophy (SMA), mRNAs containing Sm-sites are downregulated, suggesting reduced Sm-ring assembly on these mRNAs may contribute to SMA pathogenesis. Together, this study establishes that Sm-site containing mRNAs can accept Sm-rings and identifies a novel mechanism for Sm proteins in regulation of cytoplasmic mRNAs. GRAPHICAL ABSTRACT
Collapse
|
3
|
Noguchi K, Suzuki H, Abe R, Horiuchi K, Onoguchi-Mizutani R, Akimitsu N, Ogawa S, Akiyama T, Ike Y, Ino Y, Kimura Y, Ryo A, Doi H, Tanaka F, Suzuki Y, Toyoda A, Yamaguchi Y, Takahashi H. Multi-omics analysis using antibody-based in situ biotinylation technique suggests the mechanism of Cajal body formation. Cell Rep 2024; 43:114734. [PMID: 39283744 DOI: 10.1016/j.celrep.2024.114734] [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: 08/20/2023] [Revised: 04/30/2024] [Accepted: 08/23/2024] [Indexed: 09/28/2024] Open
Abstract
Membrane-less subcellular compartments play important roles in various cellular functions. Although techniques exist to identify components of cellular bodies, a comprehensive method for analyzing both static and dynamic states has not been established. Here, we apply an antibody-based in situ biotinylation proximity-labeling technique to identify components of static and dynamic nuclear bodies. Using this approach, we comprehensively identify DNA, RNA, and protein components of Cajal bodies (CBs) and then clarify their interactome. By inhibiting transcription, we capture dynamic changes in CBs. Our analysis reveals that nascent small nuclear RNAs (snRNAs) transcribed in CBs contribute to CB formation by assembling RNA-binding proteins, including frontotemporal dementia-related proteins, RNA-binding motif proteins, and heterogeneous nuclear ribonucleoproteins.
Collapse
Affiliation(s)
- Keisuke Noguchi
- Department of Molecular Biology, Yokohama City University Graduate School of Medical Science, 3-9 Fukuura, Kanazawa-ku, Yokohama, Kanagawa 236-0004, Japan
| | - Hidefumi Suzuki
- Department of Molecular Biology, Yokohama City University Graduate School of Medical Science, 3-9 Fukuura, Kanazawa-ku, Yokohama, Kanagawa 236-0004, Japan
| | - Ryota Abe
- Department of Molecular Biology, Yokohama City University Graduate School of Medical Science, 3-9 Fukuura, Kanazawa-ku, Yokohama, Kanagawa 236-0004, Japan
| | - Keiko Horiuchi
- Department of Molecular Biology, Yokohama City University Graduate School of Medical Science, 3-9 Fukuura, Kanazawa-ku, Yokohama, Kanagawa 236-0004, Japan
| | - Rena Onoguchi-Mizutani
- R&D Department, Isotope Science Center, The University of Tokyo, 2-11-16 Yayoi, Bunkyo-ku, Tokyo 113-0032, Japan
| | - Nobuyoshi Akimitsu
- R&D Department, Isotope Science Center, The University of Tokyo, 2-11-16 Yayoi, Bunkyo-ku, Tokyo 113-0032, Japan
| | - Shintaro Ogawa
- Department of Molecular Biology, Yokohama City University Graduate School of Medical Science, 3-9 Fukuura, Kanazawa-ku, Yokohama, Kanagawa 236-0004, Japan
| | - Tomohiko Akiyama
- Department of Molecular Biology, Yokohama City University Graduate School of Medical Science, 3-9 Fukuura, Kanazawa-ku, Yokohama, Kanagawa 236-0004, Japan
| | - Yoko Ike
- Department of Molecular Biology, Yokohama City University Graduate School of Medical Science, 3-9 Fukuura, Kanazawa-ku, Yokohama, Kanagawa 236-0004, Japan
| | - Yoko Ino
- Advance Medical Research Center, Yokohama City University, 3-9 Fukuura, Kanazawa-ku, Yokohama, Kanagawa 216-0004, Japan
| | - Yayoi Kimura
- Advance Medical Research Center, Yokohama City University, 3-9 Fukuura, Kanazawa-ku, Yokohama, Kanagawa 216-0004, Japan
| | - Akihide Ryo
- Department of Microbiology, Yokohama City University Graduate School of Medical Science, 3-9 Fukuura, Kanazawa-ku, Yokohama, Kanagawa 216-0004, Japan; Department of Virology III, National Institute of Infectious Diseases, 4-7-1, Gakuen Musashimurayama-shi, Tokyo 208-0011, Japan
| | - Hiroshi Doi
- Department of Neurology and Stroke Medicine, Yokohama City University, 3-9 Fukuura, Kanazawa-ku, Yokohama 236-0004, Japan
| | - Fumiaki Tanaka
- Department of Neurology and Stroke Medicine, Yokohama City University, 3-9 Fukuura, Kanazawa-ku, Yokohama 236-0004, Japan
| | - Yutaka Suzuki
- Laboratory of Systems Genomics, Department of Computational Biology and Medical Sciences, Graduate School of Frontier Sciences, The University of Tokyo, 5-1-5 Kashiwanoha, Kashiwa, Chiba 277-8562, Japan
| | - Atsushi Toyoda
- Comparative Genomics Laboratory, National Institute of Genetics, 1111 Yata, Mishima, Shizuoka 411-8540, Japan
| | - Yuki Yamaguchi
- School of Life Science and Technology, Tokyo Institute of Technology, 4259 Nagatsuta, Yokohama, Kanagawa 226-8501, Japan.
| | - Hidehisa Takahashi
- Department of Molecular Biology, Yokohama City University Graduate School of Medical Science, 3-9 Fukuura, Kanazawa-ku, Yokohama, Kanagawa 236-0004, Japan.
| |
Collapse
|
4
|
Fortuna TR, Kour S, Chimata AV, Muiños-Bühl A, Anderson EN, Nelson Iv CH, Ward C, Chauhan O, O'Brien C, Rajasundaram D, Rajan DS, Wirth B, Singh A, Pandey UB. SMN regulates GEMIN5 expression and acts as a modifier of GEMIN5-mediated neurodegeneration. Acta Neuropathol 2023; 146:477-498. [PMID: 37369805 PMCID: PMC11348892 DOI: 10.1007/s00401-023-02607-8] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/17/2023] [Revised: 06/21/2023] [Accepted: 06/22/2023] [Indexed: 06/29/2023]
Abstract
GEMIN5 is essential for core assembly of small nuclear Ribonucleoproteins (snRNPs), the building blocks of spliceosome formation. Loss-of-function mutations in GEMIN5 lead to a neurodevelopmental syndrome among patients presenting with developmental delay, motor dysfunction, and cerebellar atrophy by perturbing SMN complex protein expression and assembly. Currently, molecular determinants of GEMIN5-mediated disease have yet to be explored. Here, we identified SMN as a genetic suppressor of GEMIN5-mediated neurodegeneration in vivo. We discovered that an increase in SMN expression by either SMN gene therapy replacement or the antisense oligonucleotide (ASO), Nusinersen, significantly upregulated the endogenous levels of GEMIN5 in mammalian cells and mutant GEMIN5-derived iPSC neurons. Further, we identified a strong functional association between the expression patterns of SMN and GEMIN5 in patient Spinal Muscular Atrophy (SMA)-derived motor neurons harboring loss-of-function mutations in the SMN gene. Interestingly, SMN binds to the C-terminus of GEMIN5 and requires the Tudor domain for GEMIN5 binding and expression regulation. Finally, we show that SMN upregulation ameliorates defective snRNP biogenesis and alternative splicing defects caused by loss of GEMIN5 in iPSC neurons and in vivo. Collectively, these studies indicate that SMN acts as a regulator of GEMIN5 expression and neuropathologies.
Collapse
Affiliation(s)
- Tyler R Fortuna
- Department of Pediatrics, Children's Hospital of Pittsburgh, University of Pittsburgh Medical Center, Pittsburgh, PA, USA
| | - Sukhleen Kour
- Department of Pediatrics, Children's Hospital of Pittsburgh, University of Pittsburgh Medical Center, Pittsburgh, PA, USA
| | | | - Anixa Muiños-Bühl
- Institute of Human Genetics, Center for Molecular Medicine, Center for Rare Disorders, University of Cologne, Cologne, Germany
| | - Eric N Anderson
- Department of Pediatrics, Children's Hospital of Pittsburgh, University of Pittsburgh Medical Center, Pittsburgh, PA, USA
| | - Charlie H Nelson Iv
- Department of Pediatrics, Children's Hospital of Pittsburgh, University of Pittsburgh Medical Center, Pittsburgh, PA, USA
| | - Caroline Ward
- Department of Pediatrics, Children's Hospital of Pittsburgh, University of Pittsburgh Medical Center, Pittsburgh, PA, USA
| | - Om Chauhan
- Department of Pediatrics, Children's Hospital of Pittsburgh, University of Pittsburgh Medical Center, Pittsburgh, PA, USA
| | - Casey O'Brien
- Department of Pediatrics, Division of Health Informatics, Children's Hospital of Pittsburgh, Pittsburgh, PA, USA
| | - Dhivyaa Rajasundaram
- Department of Pediatrics, Division of Health Informatics, Children's Hospital of Pittsburgh, Pittsburgh, PA, USA
| | - Deepa S Rajan
- Department of Pediatrics, Children's Hospital of Pittsburgh, University of Pittsburgh Medical Center, Pittsburgh, PA, USA
| | - Brunhilde Wirth
- Institute of Human Genetics, Center for Molecular Medicine, Center for Rare Disorders, University of Cologne, Cologne, Germany
| | - Amit Singh
- Department of Biology, University of Dayton, Dayton, OH, USA
| | - Udai Bhan Pandey
- Department of Pediatrics, Children's Hospital of Pittsburgh, University of Pittsburgh Medical Center, Pittsburgh, PA, USA.
- Children's Neuroscience Institute, Children's Hospital of Pittsburgh, Pittsburgh, PA, USA.
| |
Collapse
|
5
|
Nikulin AD. Characteristic Features of Protein Interaction with Single- and Double-Stranded RNA. BIOCHEMISTRY (MOSCOW) 2021; 86:1025-1040. [PMID: 34488578 DOI: 10.1134/s0006297921080125] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
The review discusses differences between the specific protein interactions with single- and double-stranded RNA molecules using the data on the structure of RNA-protein complexes. Proteins interacting with the single-stranded RNAs form contacts with RNA bases, which ensures recognition of specific nucleotide sequences. Formation of such contacts with the double-stranded RNAs is hindered, so that the proteins recognize unique conformations of the RNA spatial structure and interact mainly with the RNA sugar-phosphate backbone.
Collapse
Affiliation(s)
- Alexey D Nikulin
- Institute of Protein Research, Russian Academy of Sciences, Pushchino, Moscow Region, 142290, Russia.
| |
Collapse
|
6
|
Roithová A, Feketová Z, Vaňáčová Š, Staněk D. DIS3L2 and LSm proteins are involved in the surveillance of Sm ring-deficient snRNAs. Nucleic Acids Res 2020; 48:6184-6197. [PMID: 32374871 PMCID: PMC7293007 DOI: 10.1093/nar/gkaa301] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2019] [Revised: 04/06/2020] [Accepted: 04/23/2020] [Indexed: 01/31/2023] Open
Abstract
Spliceosomal small nuclear ribonucleoprotein particles (snRNPs) undergo a complex maturation pathway containing multiple steps in the nucleus and in the cytoplasm. snRNP biogenesis is strictly proofread and several quality control checkpoints are placed along the pathway. Here, we analyzed the fate of small nuclear RNAs (snRNAs) that are unable to acquire a ring of Sm proteins. We showed that snRNAs lacking the Sm ring are unstable and accumulate in P-bodies in an LSm1-dependent manner. We further provide evidence that defective snRNAs without the Sm binding site are uridylated at the 3′ end and associate with DIS3L2 3′→5′ exoribonuclease and LSm proteins. Finally, inhibition of 5′→3′ exoribonuclease XRN1 increases association of ΔSm snRNAs with DIS3L2, which indicates competition and compensation between these two degradation enzymes. Together, we provide evidence that defective snRNAs without the Sm ring are uridylated and degraded by alternative pathways involving either DIS3L2 or LSm proteins and XRN1.
Collapse
Affiliation(s)
- Adriana Roithová
- Laboratory of RNA Biology, Institute of Molecular Genetics of the Czech Academy of Sciences, Videnska 1083, 14220 Prague, Czech Republic.,Faculty of Science, Charles University, 128 00 Prague, Czech Republic
| | - Zuzana Feketová
- CEITEC-Central European Institute of Technology, Masaryk University, Kamenice 5/A35, 625 00 Brno, Czech Republic
| | - Štěpánka Vaňáčová
- CEITEC-Central European Institute of Technology, Masaryk University, Kamenice 5/A35, 625 00 Brno, Czech Republic
| | - David Staněk
- Laboratory of RNA Biology, Institute of Molecular Genetics of the Czech Academy of Sciences, Videnska 1083, 14220 Prague, Czech Republic
| |
Collapse
|
7
|
Yi H, Mu L, Shen C, Kong X, Wang Y, Hou Y, Zhang R. Negative cooperativity between Gemin2 and RNA provides insights into RNA selection and the SMN complex's release in snRNP assembly. Nucleic Acids Res 2020; 48:895-911. [PMID: 31799625 PMCID: PMC6954390 DOI: 10.1093/nar/gkz1135] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/14/2019] [Revised: 11/14/2019] [Accepted: 11/21/2019] [Indexed: 02/05/2023] Open
Abstract
The assembly of snRNP cores, in which seven Sm proteins, D1/D2/F/E/G/D3/B, form a ring around the nonameric Sm site of snRNAs, is the early step of spliceosome formation and essential to eukaryotes. It is mediated by the PMRT5 and SMN complexes sequentially in vivo. SMN deficiency causes neurodegenerative disease spinal muscular atrophy (SMA). How the SMN complex assembles snRNP cores is largely unknown, especially how the SMN complex achieves high RNA assembly specificity and how it is released. Here we show, using crystallographic and biochemical approaches, that Gemin2 of the SMN complex enhances RNA specificity of SmD1/D2/F/E/G via a negative cooperativity between Gemin2 and RNA in binding SmD1/D2/F/E/G. Gemin2, independent of its N-tail, constrains the horseshoe-shaped SmD1/D2/F/E/G from outside in a physiologically relevant, narrow state, enabling high RNA specificity. Moreover, the assembly of RNAs inside widens SmD1/D2/F/E/G, causes the release of Gemin2/SMN allosterically and allows SmD3/B to join. The assembly of SmD3/B further facilitates the release of Gemin2/SMN. This is the first to show negative cooperativity in snRNP assembly, which provides insights into RNA selection and the SMN complex's release. These findings reveal a basic mechanism of snRNP core assembly and facilitate pathogenesis studies of SMA.
Collapse
Affiliation(s)
- Hongfei Yi
- Department of Ophthalmology, State Key Laboratory of Biotherapy, West China Hospital, Sichuan University and Collaborative Innovation Center for Biotherapy, Chengdu 610041, P.R. China
| | - Li Mu
- Department of Ophthalmology, State Key Laboratory of Biotherapy, West China Hospital, Sichuan University and Collaborative Innovation Center for Biotherapy, Chengdu 610041, P.R. China
| | - Congcong Shen
- Department of Ophthalmology, State Key Laboratory of Biotherapy, West China Hospital, Sichuan University and Collaborative Innovation Center for Biotherapy, Chengdu 610041, P.R. China
| | - Xi Kong
- Department of Ophthalmology, State Key Laboratory of Biotherapy, West China Hospital, Sichuan University and Collaborative Innovation Center for Biotherapy, Chengdu 610041, P.R. China
| | - Yingzhi Wang
- Department of Ophthalmology, State Key Laboratory of Biotherapy, West China Hospital, Sichuan University and Collaborative Innovation Center for Biotherapy, Chengdu 610041, P.R. China
| | - Yan Hou
- Department of Ophthalmology, State Key Laboratory of Biotherapy, West China Hospital, Sichuan University and Collaborative Innovation Center for Biotherapy, Chengdu 610041, P.R. China
| | - Rundong Zhang
- Department of Ophthalmology, State Key Laboratory of Biotherapy, West China Hospital, Sichuan University and Collaborative Innovation Center for Biotherapy, Chengdu 610041, P.R. China
| |
Collapse
|
8
|
Venters CC, Oh JM, Di C, So BR, Dreyfuss G. U1 snRNP Telescripting: Suppression of Premature Transcription Termination in Introns as a New Layer of Gene Regulation. Cold Spring Harb Perspect Biol 2019; 11:11/2/a032235. [PMID: 30709878 DOI: 10.1101/cshperspect.a032235] [Citation(s) in RCA: 53] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
Recent observations showed that nascent RNA polymerase II transcripts, pre-mRNAs, and noncoding RNAs are highly susceptible to premature 3'-end cleavage and polyadenylation (PCPA) from numerous intronic cryptic polyadenylation signals (PASs). The importance of this in gene regulation was not previously appreciated as PASs, despite their prevalence, were thought to be active in terminal exons at gene ends. Unexpectedly, antisense oligonucleotide interference with U1 snRNA base-pairing to 5' splice sites, which is necessary for U1 snRNP's (U1) function in splicing, caused widespread PCPA in metazoans. This uncovered U1's PCPA suppression activity, termed telescripting, as crucial for full-length transcription in thousands of vertebrate genes, providing a general role in transcription elongation control. Progressive intron-size expansion in metazoan evolution greatly increased PCPA vulnerability and dependence on U1 telescripting. We describe how these observations unfolded and discuss U1 telescripting's role in shaping the transcriptome.
Collapse
Affiliation(s)
- Christopher C Venters
- Howard Hughes Medical Institute, Department of Biochemistry and Biophysics, University of Pennsylvania School of Medicine, Philadelphia, Pennsylvania 19104
| | - Jung-Min Oh
- Howard Hughes Medical Institute, Department of Biochemistry and Biophysics, University of Pennsylvania School of Medicine, Philadelphia, Pennsylvania 19104
| | - Chao Di
- Howard Hughes Medical Institute, Department of Biochemistry and Biophysics, University of Pennsylvania School of Medicine, Philadelphia, Pennsylvania 19104
| | - Byung Ran So
- Howard Hughes Medical Institute, Department of Biochemistry and Biophysics, University of Pennsylvania School of Medicine, Philadelphia, Pennsylvania 19104
| | - Gideon Dreyfuss
- Howard Hughes Medical Institute, Department of Biochemistry and Biophysics, University of Pennsylvania School of Medicine, Philadelphia, Pennsylvania 19104
| |
Collapse
|
9
|
Schmidt D, Reuter H, Hüttner K, Ruhe L, Rabert F, Seebeck F, Irimia M, Solana J, Bartscherer K. The Integrator complex regulates differential snRNA processing and fate of adult stem cells in the highly regenerative planarian Schmidtea mediterranea. PLoS Genet 2018; 14:e1007828. [PMID: 30557303 PMCID: PMC6312358 DOI: 10.1371/journal.pgen.1007828] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/06/2017] [Revised: 12/31/2018] [Accepted: 11/12/2018] [Indexed: 02/07/2023] Open
Abstract
In multicellular organisms, cell type diversity and fate depend on specific sets of transcript isoforms generated by post-transcriptional RNA processing. Here, we used Schmidtea mediterranea, a flatworm with extraordinary regenerative abilities and a large pool of adult stem cells, as an in vivo model to study the role of Uridyl-rich small nuclear RNAs (UsnRNAs), which participate in multiple RNA processing reactions including splicing, in stem cell regulation. We characterized the planarian UsnRNA repertoire, identified stem cell-enriched variants and obtained strong evidence for an increased rate of UsnRNA 3'-processing in stem cells compared to their differentiated counterparts. Consistently, components of the Integrator complex showed stem cell-enriched expression and their depletion by RNAi disrupted UsnRNA processing resulting in global changes of splicing patterns and reduced processing of histone mRNAs. Interestingly, loss of Integrator complex function disrupted both stem cell maintenance and regeneration of tissues. Our data show that the function of the Integrator complex in UsnRNA 3'-processing is conserved in planarians and essential for maintaining their stem cell pool. We propose that cell type-specific modulation of UsnRNA composition and maturation contributes to in vivo cell fate choices, such as stem cell self-renewal in planarians.
Collapse
Affiliation(s)
- David Schmidt
- Max Planck Institute for Molecular Biomedicine, Münster, Germany
- Medical Faculty, University of Münster, Münster, Germany
- * E-mail: (DS); (KB)
| | - Hanna Reuter
- Max Planck Institute for Molecular Biomedicine, Münster, Germany
- Medical Faculty, University of Münster, Münster, Germany
| | - Katja Hüttner
- Max Planck Institute for Molecular Biomedicine, Münster, Germany
- Medical Faculty, University of Münster, Münster, Germany
| | - Larissa Ruhe
- Max Planck Institute for Molecular Biomedicine, Münster, Germany
- Medical Faculty, University of Münster, Münster, Germany
| | - Franziska Rabert
- Max Planck Institute for Molecular Biomedicine, Münster, Germany
- Medical Faculty, University of Münster, Münster, Germany
| | - Florian Seebeck
- Max Planck Institute for Molecular Biomedicine, Münster, Germany
- Medical Faculty, University of Münster, Münster, Germany
| | - Manuel Irimia
- Centre for Genomic Regulation (CRG), The Barcelona Institute of Science and Technology, Barcelona, Spain
- Universitat Pompeu Fabra, Barcelona, Spain
| | - Jordi Solana
- Systems Biology of Gene Regulatory Elements, Berlin Institute for Medical Systems Biology, Max-Delbrück Center for Molecular Medicine, Berlin, Germany
| | - Kerstin Bartscherer
- Max Planck Institute for Molecular Biomedicine, Münster, Germany
- Medical Faculty, University of Münster, Münster, Germany
- Hubrecht Institute for Developmental Biology and Stem Cell Research, CT Utrecht, The Netherlands
- * E-mail: (DS); (KB)
| |
Collapse
|
10
|
Chaytow H, Huang YT, Gillingwater TH, Faller KME. The role of survival motor neuron protein (SMN) in protein homeostasis. Cell Mol Life Sci 2018; 75:3877-3894. [PMID: 29872871 PMCID: PMC6182345 DOI: 10.1007/s00018-018-2849-1] [Citation(s) in RCA: 129] [Impact Index Per Article: 18.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/2018] [Revised: 05/30/2018] [Accepted: 05/31/2018] [Indexed: 12/11/2022]
Abstract
Ever since loss of survival motor neuron (SMN) protein was identified as the direct cause of the childhood inherited neurodegenerative disorder spinal muscular atrophy, significant efforts have been made to reveal the molecular functions of this ubiquitously expressed protein. Resulting research demonstrated that SMN plays important roles in multiple fundamental cellular homeostatic pathways, including a well-characterised role in the assembly of the spliceosome and biogenesis of ribonucleoproteins. More recent studies have shown that SMN is also involved in other housekeeping processes, including mRNA trafficking and local translation, cytoskeletal dynamics, endocytosis and autophagy. Moreover, SMN has been shown to influence mitochondria and bioenergetic pathways as well as regulate function of the ubiquitin-proteasome system. In this review, we summarise these diverse functions of SMN, confirming its key role in maintenance of the homeostatic environment of the cell.
Collapse
Affiliation(s)
- Helena Chaytow
- Euan MacDonald Centre for Motor Neurone Disease Research, University of Edinburgh, Edinburgh, UK
- Edinburgh Medical School: Biomedical Sciences, University of Edinburgh, Edinburgh, UK
| | - Yu-Ting Huang
- Euan MacDonald Centre for Motor Neurone Disease Research, University of Edinburgh, Edinburgh, UK
- Edinburgh Medical School: Biomedical Sciences, University of Edinburgh, Edinburgh, UK
| | - Thomas H Gillingwater
- Euan MacDonald Centre for Motor Neurone Disease Research, University of Edinburgh, Edinburgh, UK.
- Edinburgh Medical School: Biomedical Sciences, University of Edinburgh, Edinburgh, UK.
| | - Kiterie M E Faller
- Euan MacDonald Centre for Motor Neurone Disease Research, University of Edinburgh, Edinburgh, UK
- Edinburgh Medical School: Biomedical Sciences, University of Edinburgh, Edinburgh, UK
- Royal (Dick) School of Veterinary Studies, University of Edinburgh, Edinburgh, UK
| |
Collapse
|
11
|
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: 1.9] [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.
Collapse
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
| |
Collapse
|
12
|
Xu C, Ishikawa H, Izumikawa K, Li L, He H, Nobe Y, Yamauchi Y, Shahjee HM, Wu XH, Yu YT, Isobe T, Takahashi N, Min J. Structural insights into Gemin5-guided selection of pre-snRNAs for snRNP assembly. Genes Dev 2016; 30:2376-2390. [PMID: 27881600 PMCID: PMC5131778 DOI: 10.1101/gad.288340.116] [Citation(s) in RCA: 52] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2016] [Accepted: 09/26/2016] [Indexed: 12/26/2022]
Abstract
Xu et al. show that the WD40 domain of Gemin5 is both necessary and sufficient for binding the Sm site of pre-snRNAs. They also determined the crystal structures of the WD40 domain of Gemin5 in complex with the Sm site or m7G cap of pre-snRNA. In cytoplasm, the survival of motor neuron (SMN) complex delivers pre-small nuclear RNAs (pre-snRNAs) to the heptameric Sm ring for the assembly of the ring complex on pre-snRNAs at the conserved Sm site [A(U)4–6G]. Gemin5, a WD40 protein component of the SMN complex, is responsible for recognizing pre-snRNAs. In addition, Gemin5 has been reported to specifically bind to the m7G cap. In this study, we show that the WD40 domain of Gemin5 is both necessary and sufficient for binding the Sm site of pre-snRNAs by isothermal titration calorimetry (ITC) and mutagenesis assays. We further determined the crystal structures of the WD40 domain of Gemin5 in complex with the Sm site or m7G cap of pre-snRNA, which reveal that the WD40 domain of Gemin5 recognizes the Sm site and m7G cap of pre-snRNAs via two distinct binding sites by respective base-specific interactions. In addition, we also uncovered a novel role of Gemin5 in escorting the truncated forms of U1 pre-snRNAs for proper disposal. Overall, the elucidated Gemin5 structures will contribute to a better understanding of Gemin5 in small nuclear ribonucleic protein (snRNP) biogenesis as well as, potentially, other cellular activities.
Collapse
Affiliation(s)
- Chao Xu
- Hefei National Laboratory for Physical Sciences at Microscale, Hefei Science Center of CAS, Chinese Academy of Science, School of Life Sciences, University of Science and Technology of China, Hefei, Anhui 230027, People's Republic of China.,Key Laboratory of Structural Biology, Hefei Science Center of CAS, Chinese Academy of Science, School of Life Sciences, University of Science and Technology of China, Hefei, Anhui 230027, People's Republic of China.,Structural Genomics Consortium, University of Toronto, Toronto, Ontario M5G 1L7, Canada
| | - Hideaki Ishikawa
- Department of Applied Biological Science, Graduate School of Agriculture and Global Innovation Research Organization, Tokyo University of Agriculture and Technology, Fuchu-Shi, Tokyo 183-8509, Japan
| | - Keiichi Izumikawa
- Department of Applied Biological Science, Graduate School of Agriculture and Global Innovation Research Organization, Tokyo University of Agriculture and Technology, Fuchu-Shi, Tokyo 183-8509, Japan
| | - Li Li
- Structural Genomics Consortium, University of Toronto, Toronto, Ontario M5G 1L7, Canada
| | - Hao He
- Structural Genomics Consortium, University of Toronto, Toronto, Ontario M5G 1L7, Canada
| | - Yuko Nobe
- Department of Chemistry, Tokyo Metropolitan University, Hachiouji-shi, Tokyo 192-0397, Japan
| | - Yoshio Yamauchi
- Department of Chemistry, Tokyo Metropolitan University, Hachiouji-shi, Tokyo 192-0397, Japan
| | - Hanief M Shahjee
- Department of Biochemistry and Biophysics, Center for RNA Biology, University of Rochester School of Medicine and Dentistry, Rochester, New York 14642, USA
| | - Xian-Hui Wu
- Structural Genomics Consortium, University of Toronto, Toronto, Ontario M5G 1L7, Canada
| | - Yi-Tao Yu
- Department of Biochemistry and Biophysics, Center for RNA Biology, University of Rochester School of Medicine and Dentistry, Rochester, New York 14642, USA
| | - Toshiaki Isobe
- Department of Chemistry, Tokyo Metropolitan University, Hachiouji-shi, Tokyo 192-0397, Japan
| | - Nobuhiro Takahashi
- Department of Applied Biological Science, Graduate School of Agriculture and Global Innovation Research Organization, Tokyo University of Agriculture and Technology, Fuchu-Shi, Tokyo 183-8509, Japan
| | - Jinrong Min
- Structural Genomics Consortium, University of Toronto, Toronto, Ontario M5G 1L7, Canada.,Department of Physiology, University of Toronto, Toronto, Ontario M5S 1A8, Canada
| |
Collapse
|
13
|
Jin W, Wang Y, Liu CP, Yang N, Jin M, Cong Y, Wang M, Xu RM. Structural basis for snRNA recognition by the double-WD40 repeat domain of Gemin5. Genes Dev 2016; 30:2391-2403. [PMID: 27881601 PMCID: PMC5131779 DOI: 10.1101/gad.291377.116] [Citation(s) in RCA: 39] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2016] [Accepted: 10/17/2016] [Indexed: 12/21/2022]
Abstract
Assembly of the spliceosomal small nuclear ribonucleoparticle (snRNP) core requires the participation of the multisubunit SMN (survival of motor neuron) complex, which contains SMN and several Gemin proteins. The SMN and Gemin2 subunits directly bind Sm proteins, and Gemin5 is required for snRNP biogenesis and has been implicated in snRNA recognition. The RNA sequence required for snRNP assembly includes the Sm site and an adjacent 3' stem-loop, but a precise understanding of Gemin5's RNA-binding specificity is lacking. Here we show that the N-terminal half of Gemin5, which is composed of two juxtaposed seven-bladed WD40 repeat domains, recognizes the Sm site. The tandem WD40 repeat domains are rigidly held together to form a contiguous RNA-binding surface. RNA-contacting residues are located mostly on loops between β strands on the apical surface of the WD40 domains. Structural and biochemical analyses show that base-stacking interactions involving four aromatic residues and hydrogen bonding by a pair of arginines are crucial for specific recognition of the Sm sequence. We also show that an adenine immediately 5' to the Sm site is required for efficient binding and that Gemin5 can bind short RNA oligos in an alternative mode. Our results provide mechanistic understandings of Gemin5's snRNA-binding specificity as well as valuable insights into the molecular mechanism of RNA binding by WD40 repeat proteins in general.
Collapse
Affiliation(s)
- Wenxing Jin
- National Laboratory of Biomacromolecules, CAS Center for Excellence in Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, Beijing 100101, China
| | - Yi Wang
- National Laboratory of Biomacromolecules, CAS Center for Excellence in Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, Beijing 100101, China.,University of Chinese Academy of Sciences, Beijing 100049, China
| | - Chao-Pei Liu
- National Laboratory of Biomacromolecules, CAS Center for Excellence in Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, Beijing 100101, China
| | - Na Yang
- National Laboratory of Biomacromolecules, CAS Center for Excellence in Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, Beijing 100101, China.,University of Chinese Academy of Sciences, Beijing 100049, China
| | - Mingliang Jin
- University of Chinese Academy of Sciences, Beijing 100049, China.,National Center for Protein Science Shanghai, State Key Laboratory of Molecular Biology, Institute of Biochemistry and Cell Biology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai 201210, China
| | - Yao Cong
- National Center for Protein Science Shanghai, State Key Laboratory of Molecular Biology, Institute of Biochemistry and Cell Biology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai 201210, China
| | - Mingzhu Wang
- National Laboratory of Biomacromolecules, CAS Center for Excellence in Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, Beijing 100101, China
| | - Rui-Ming Xu
- National Laboratory of Biomacromolecules, CAS Center for Excellence in Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, Beijing 100101, China.,University of Chinese Academy of Sciences, Beijing 100049, China
| |
Collapse
|
14
|
So BR, Wan L, Zhang Z, Li P, Babiash E, Duan J, Younis I, Dreyfuss G. A U1 snRNP-specific assembly pathway reveals the SMN complex as a versatile hub for RNP exchange. Nat Struct Mol Biol 2016; 23:225-30. [PMID: 26828962 PMCID: PMC4834709 DOI: 10.1038/nsmb.3167] [Citation(s) in RCA: 65] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2015] [Accepted: 01/04/2016] [Indexed: 02/01/2023]
Abstract
Despite equal snRNP stoichiometry in spliceosomes, U1 snRNP (U1) is typically the most abundant vertebrate snRNP. Mechanisms regulating U1 overabundance and snRNP repertoire are unknown. In Sm-core assembly, a key snRNP-biogenesis step mediated by the SMN complex, the snRNA-specific RNA-binding protein (RBP) Gemin5 delivers pre-snRNAs, which join SMN-Gemin2-recruited Sm proteins. We show that the human U1-specific RBP U1-70K can bridge pre-U1 to SMN-Gemin2-Sm, in a Gemin5-independent manner, thus establishing an additional and U1-exclusive Sm core-assembly pathway. U1-70K hijacks SMN-Gemin2-Sm, enhancing Sm-core assembly on U1s and inhibiting that on other snRNAs, thereby promoting U1 overabundance and regulating snRNP repertoire. SMN-Gemin2's ability to facilitate transactions between different RBPs and RNAs explains its multi-RBP valency and the myriad transcriptome perturbations associated with SMN deficiency in neurodegenerative spinal muscular atrophy. We propose that SMN-Gemin2 is a versatile hub for RNP exchange that functions broadly in RNA metabolism.
Collapse
Affiliation(s)
- Byung Ran So
- Howard Hughes Medical Institute, Department of Biochemistry and Biophysics, University of Pennsylvania School of Medicine, Philadelphia, Pennsylvania, USA
| | - Lili Wan
- Howard Hughes Medical Institute, Department of Biochemistry and Biophysics, University of Pennsylvania School of Medicine, Philadelphia, Pennsylvania, USA
| | - Zhenxi Zhang
- Howard Hughes Medical Institute, Department of Biochemistry and Biophysics, University of Pennsylvania School of Medicine, Philadelphia, Pennsylvania, USA
| | - Pilong Li
- Howard Hughes Medical Institute, Department of Biochemistry and Biophysics, University of Pennsylvania School of Medicine, Philadelphia, Pennsylvania, USA
| | - Eric Babiash
- Howard Hughes Medical Institute, Department of Biochemistry and Biophysics, University of Pennsylvania School of Medicine, Philadelphia, Pennsylvania, USA
| | - Jingqi Duan
- Howard Hughes Medical Institute, Department of Biochemistry and Biophysics, University of Pennsylvania School of Medicine, Philadelphia, Pennsylvania, USA
| | - Ihab Younis
- Howard Hughes Medical Institute, Department of Biochemistry and Biophysics, University of Pennsylvania School of Medicine, Philadelphia, Pennsylvania, USA
| | - Gideon Dreyfuss
- Howard Hughes Medical Institute, Department of Biochemistry and Biophysics, University of Pennsylvania School of Medicine, Philadelphia, Pennsylvania, USA
| |
Collapse
|
15
|
Hyjek M, Wojciechowska N, Rudzka M, Kołowerzo-Lubnau A, Smoliński DJ. Spatial regulation of cytoplasmic snRNP assembly at the cellular level. JOURNAL OF EXPERIMENTAL BOTANY 2015; 66:7019-30. [PMID: 26320237 PMCID: PMC4765780 DOI: 10.1093/jxb/erv399] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/07/2023]
Abstract
Small nuclear ribonucleoproteins (snRNPs) play a crucial role in pre-mRNA splicing in all eukaryotic cells. In contrast to the relatively broad knowledge on snRNP assembly within the nucleus, the spatial organization of the cytoplasmic stages of their maturation remains poorly understood. Nevertheless, sparse research indicates that, similar to the nuclear steps, the crucial processes of cytoplasmic snRNP assembly may also be strictly spatially regulated. In European larch microsporocytes, it was determined that the cytoplasmic assembly of snRNPs within a cell might occur in two distinct spatial manners, which depend on the rate of de novo snRNP formation in relation to the steady state of these particles within the nucleus. During periods of moderate expression of splicing elements, the cytoplasmic assembly of snRNPs occurred diffusely throughout the cytoplasm. Increased expression of both Sm proteins and U snRNA triggered the accumulation of these particles within distinct, non-membranous RNP-rich granules, which are referred to as snRNP-rich cytoplasmic bodies.
Collapse
Affiliation(s)
- Malwina Hyjek
- Department of Cell Biology, Faculty of Biology and Environmental Protection, Nicolaus Copernicus University, Lwowska 1, Toruń, 87-100, Poland Centre For Modern Interdisciplinary Technologies, Nicolaus Copernicus University, Wileńska 4, 87-100 Toruń Poland
| | - Natalia Wojciechowska
- Department of Cell Biology, Faculty of Biology and Environmental Protection, Nicolaus Copernicus University, Lwowska 1, Toruń, 87-100, Poland Department of General Botany, Institute of Experimental Biology, Faculty of Biology, A. Mickiewicz University, Umultowska 89, 61-614 Poznań, Poland
| | - Magda Rudzka
- Department of Cell Biology, Faculty of Biology and Environmental Protection, Nicolaus Copernicus University, Lwowska 1, Toruń, 87-100, Poland Centre For Modern Interdisciplinary Technologies, Nicolaus Copernicus University, Wileńska 4, 87-100 Toruń Poland
| | - Agnieszka Kołowerzo-Lubnau
- Department of Cell Biology, Faculty of Biology and Environmental Protection, Nicolaus Copernicus University, Lwowska 1, Toruń, 87-100, Poland Centre For Modern Interdisciplinary Technologies, Nicolaus Copernicus University, Wileńska 4, 87-100 Toruń Poland
| | - Dariusz Jan Smoliński
- Department of Cell Biology, Faculty of Biology and Environmental Protection, Nicolaus Copernicus University, Lwowska 1, Toruń, 87-100, Poland Centre For Modern Interdisciplinary Technologies, Nicolaus Copernicus University, Wileńska 4, 87-100 Toruń Poland
| |
Collapse
|
16
|
Sloan KE, Gleizes PE, Bohnsack MT. Nucleocytoplasmic Transport of RNAs and RNA-Protein Complexes. J Mol Biol 2015; 428:2040-59. [PMID: 26434509 DOI: 10.1016/j.jmb.2015.09.023] [Citation(s) in RCA: 51] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2015] [Revised: 09/26/2015] [Accepted: 09/28/2015] [Indexed: 12/15/2022]
Abstract
RNAs and ribonucleoprotein complexes (RNPs) play key roles in mediating and regulating gene expression. In eukaryotes, most RNAs are transcribed, processed and assembled with proteins in the nucleus and then either function in the cytoplasm or also undergo a cytoplasmic phase in their biogenesis. This compartmentalization ensures that sequential steps in gene expression and RNP production are performed in the correct order and it allows important quality control mechanisms that prevent the involvement of aberrant RNAs/RNPs in these cellular pathways. The selective exchange of RNAs/RNPs between the nucleus and cytoplasm is enabled by nuclear pore complexes, which function as gateways between these compartments. RNA/RNP transport is facilitated by a range of nuclear transport receptors and adaptors, which are specifically recruited to their cargos and mediate interactions with nucleoporins to allow directional translocation through nuclear pore complexes. While some transport factors are only responsible for the export/import of a certain class of RNA/RNP, others are multifunctional and, in the case of large RNPs, several export factors appear to work together to bring about export. Recent structural studies have revealed aspects of the mechanisms employed by transport receptors to enable specific cargo recognition, and genome-wide approaches have provided the first insights into the diverse composition of pre-mRNPs during export. Furthermore, the regulation of RNA/RNP export is emerging as an important means to modulate gene expression under stress conditions and in disease.
Collapse
Affiliation(s)
- Katherine E Sloan
- Institute for Molecular Biology, Goettingen University Medical Department, 37073 Goettingen, Germany
| | - Pierre-Emmanuel Gleizes
- Laboratoire de Biologie Moléculaire Eucaryote, UMR 5099, Université de Toulouse-Paul Sabatier, CNRS, Toulouse, France
| | - Markus T Bohnsack
- Institute for Molecular Biology, Goettingen University Medical Department, 37073 Goettingen, Germany; Goettingen Centre for Molecular Biosciences, Georg-August-University, 37075 Goettingen, Germany.
| |
Collapse
|
17
|
Tsalikis J, Tattoli I, Ling A, Sorbara MT, Croitoru DO, Philpott DJ, Girardin SE. Intracellular Bacterial Pathogens Trigger the Formation of U Small Nuclear RNA Bodies (U Bodies) through Metabolic Stress Induction. J Biol Chem 2015; 290:20904-20918. [PMID: 26134566 DOI: 10.1074/jbc.m115.659466] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/16/2015] [Indexed: 12/30/2022] Open
Abstract
Invasive bacterial pathogens induce an amino acid starvation (AAS) response in infected host cells that controls host defense in part by promoting autophagy. However, whether AAS has additional significant effects on the host response to intracellular bacteria remains poorly characterized. Here we showed that Shigella, Salmonella, and Listeria interfere with spliceosomal U snRNA maturation in the cytosol. Bacterial infection resulted in the rerouting of U snRNAs and their cytoplasmic escort, the survival motor neuron (SMN) complex, to processing bodies, thus forming U snRNA bodies (U bodies). This process likely contributes to the decline in the cytosolic levels of U snRNAs and of the SMN complex proteins SMN and DDX20 that we observed in infected cells. U body formation was triggered by membrane damage in infected cells and was associated with the induction of metabolic stresses, such as AAS or endoplasmic reticulum stress. Mechanistically, targeting of U snRNAs to U bodies was regulated by translation initiation inhibition and the ATF4/ATF3 pathway, and U bodies rapidly disappeared upon removal of the stress, suggesting that their accumulation represented an adaptive response to metabolic stress. Importantly, this process likely contributed to shape the host response to invasive bacteria because down-regulation of DDX20 expression using short hairpin RNA (shRNA) amplified ATF3- and NF-κB-dependent signaling. Together, these results identify a critical role for metabolic stress and invasive bacterial pathogens in U body formation and suggest that this process contributes to host defense.
Collapse
Affiliation(s)
- Jessica Tsalikis
- Departments of Laboratory Medicine and Pathobiology, University of Toronto, Toronto M6G 2T6, Canada
| | - Ivan Tattoli
- Departments of Laboratory Medicine and Pathobiology, University of Toronto, Toronto M6G 2T6, Canada; Departments of Immunology, University of Toronto, Toronto M6G 2T6, Canada
| | - Arthur Ling
- Departments of Laboratory Medicine and Pathobiology, University of Toronto, Toronto M6G 2T6, Canada
| | - Matthew T Sorbara
- Departments of Immunology, University of Toronto, Toronto M6G 2T6, Canada
| | - David O Croitoru
- Departments of Laboratory Medicine and Pathobiology, University of Toronto, Toronto M6G 2T6, Canada
| | - Dana J Philpott
- Departments of Immunology, University of Toronto, Toronto M6G 2T6, Canada
| | - Stephen E Girardin
- Departments of Laboratory Medicine and Pathobiology, University of Toronto, Toronto M6G 2T6, Canada.
| |
Collapse
|
18
|
Seng CO, Magee C, Young PJ, Lorson CL, Allen JP. The SMN structure reveals its crucial role in snRNP assembly. Hum Mol Genet 2015; 24:2138-46. [PMID: 25561692 DOI: 10.1093/hmg/ddu734] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
The spliceosome plays a fundamental role in RNA metabolism by facilitating pre-RNA splicing. To understand how this essential complex is formed, we have used protein crystallography to determine the first complete structures of the key assembler protein, SMN, and the truncated isoform, SMNΔ7, which is found in patients with the disease spinal muscular atrophy (SMA). Comparison of the structures of SMN and SMNΔ7 shows many similar features, including the presence of two Tudor domains, but significant differences are observed in the C-terminal domain, including 12 additional amino acid residues encoded by exon 7 in SMN compared with SMNΔ7. Mapping of missense point mutations found in some SMA patients reveals clustering around three spatial locations, with the largest cluster found in the C-terminal domain. We propose a structural model of SMN binding with the Gemin2 protein and a heptameric Sm ring, revealing a critical assembly role of the residues 260-294, with the differences at the C-terminus of SMNΔ7 compared with SMN likely leading to loss of small nuclear ribonucleoprotein (snRNP) assembly. The SMN complex is proposed to form a dimer driven by formation of a glycine zipper involving α helix formed by amino acid residues 263-294. These results explain how structural changes of SMN give rise to loss of SMN-mediated snRNP assembly and support the hypothesis that this loss results in atrophy of neurons in SMA.
Collapse
Affiliation(s)
- Chenda O Seng
- Department of Chemistry and Biochemistry, Arizona State University, Tempe, AZ 85287, USA and
| | - Craig Magee
- Department of Chemistry and Biochemistry, Arizona State University, Tempe, AZ 85287, USA and
| | - Philip J Young
- Department of Veterinary Pathology, Bond Life Sciences Center, College of Veterinary Medicine, University of Missouri, Columbia, MO 65211, USA
| | - Christian L Lorson
- Department of Veterinary Pathology, Bond Life Sciences Center, College of Veterinary Medicine, University of Missouri, Columbia, MO 65211, USA
| | - James P Allen
- Department of Chemistry and Biochemistry, Arizona State University, Tempe, AZ 85287, USA and
| |
Collapse
|
19
|
Baumgartner M, Lemoine C, Al Seesi S, Karunakaran DKP, Sturrock N, Banday AR, Kilcollins AM, Mandoiu I, Kanadia RN. Minor splicing snRNAs are enriched in the developing mouse CNS and are crucial for survival of differentiating retinal neurons. Dev Neurobiol 2014; 75:895-907. [PMID: 25492806 DOI: 10.1002/dneu.22257] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/26/2014] [Revised: 11/24/2014] [Accepted: 12/08/2014] [Indexed: 12/21/2022]
Abstract
In eukaryotes, gene expression requires splicing, which starts with the identification of exon-intron boundaries by the small, nuclear RNA (snRNAs) of the spliceosome, aided by associated proteins. In the mammalian genome, <1% of introns lack canonical exon-intron boundary sequences and cannot be spliced by the canonical splicing machinery. These introns are spliced by the minor spliceosome, consisting of unique snRNAs (U11, U12, U4atac, and U6atac). The importance of the minor spliceosome is underscored by the disease microcephalic osteodysplastic primordial dwarfism type 1 (MOPD1), which is caused by mutation in U4atac. Thus, it is important to understand the expression and function of the minor spliceosome and its targets in mammalian development, for which we used the mouse as our model. Here, we report enrichment of the minor snRNAs in the developing head/central nervous system (CNS) between E9.5 and E12.5, along with enrichment of these snRNAs in differentiating retinal neurons. Moreover, dynamic expression kinetics of minor intron-containing genes (MIGs) was observed across retinal development. DAVID analysis of MIGs that were cotranscriptionally upregulated embryonically revealed enrichment for RNA metabolism and cell cycle regulation. In contrast, MIGs that were cotranscriptionally upregulated postnatally revealed enrichment for protein localization/transport, vesicle-mediated transport, and calcium transport. Finally, we used U12 morpholino to inactivate the minor spliceosome in the postnatal retina, which resulted in apoptosis of differentiating retinal neurons. Taken together, our data suggest that the minor spliceosome may have distinct functions in embryonic versus postnatal development. Importantly, we show that the minor spliceosome is crucial for the survival of terminally differentiating retinal neurons.
Collapse
Affiliation(s)
- Marybeth Baumgartner
- Department of Physiology and Neurobiology, University of Connecticut, Storrs, Connecticut, 06269
| | - Christopher Lemoine
- Department of Physiology and Neurobiology, University of Connecticut, Storrs, Connecticut, 06269
| | - Sahar Al Seesi
- Department of Computer Science and Engineering, University of Connecticut, Storrs, Connecticut, 06269
| | | | - Nikita Sturrock
- Department of Physiology and Neurobiology, University of Connecticut, Storrs, Connecticut, 06269
| | - Abdul Rouf Banday
- Department of Physiology and Neurobiology, University of Connecticut, Storrs, Connecticut, 06269
| | - Ashley M Kilcollins
- Department of Physiology and Neurobiology, University of Connecticut, Storrs, Connecticut, 06269
| | - Ion Mandoiu
- Department of Computer Science and Engineering, University of Connecticut, Storrs, Connecticut, 06269
| | - Rahul N Kanadia
- Department of Physiology and Neurobiology, University of Connecticut, Storrs, Connecticut, 06269
| |
Collapse
|
20
|
Li DK, Tisdale S, Lotti F, Pellizzoni L. SMN control of RNP assembly: from post-transcriptional gene regulation to motor neuron disease. Semin Cell Dev Biol 2014; 32:22-9. [PMID: 24769255 DOI: 10.1016/j.semcdb.2014.04.026] [Citation(s) in RCA: 124] [Impact Index Per Article: 11.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/26/2014] [Accepted: 04/17/2014] [Indexed: 11/25/2022]
Abstract
At the post-transcriptional level, expression of protein-coding genes is controlled by a series of RNA regulatory events including nuclear processing of primary transcripts, transport of mature mRNAs to specific cellular compartments, translation and ultimately, turnover. These processes are orchestrated through the dynamic association of mRNAs with RNA binding proteins and ribonucleoprotein (RNP) complexes. Accurate formation of RNPs in vivo is fundamentally important to cellular development and function, and its impairment often leads to human disease. The survival motor neuron (SMN) protein is key to this biological paradigm: SMN is essential for the biogenesis of various RNPs that function in mRNA processing, and genetic mutations leading to SMN deficiency cause the neurodegenerative disease spinal muscular atrophy. Here we review the expanding role of SMN in the regulation of gene expression through its multiple functions in RNP assembly. We discuss advances in our understanding of SMN activity as a chaperone of RNPs and how disruption of SMN-dependent RNA pathways can cause motor neuron disease.
Collapse
Affiliation(s)
- Darrick K Li
- Center for Motor Neuron Biology and Disease, Columbia University, New York, NY 10032, USA; Department of Pathology and Cell Biology, Columbia University, New York, NY 10032, USA
| | - Sarah Tisdale
- Center for Motor Neuron Biology and Disease, Columbia University, New York, NY 10032, USA; Department of Pathology and Cell Biology, Columbia University, New York, NY 10032, USA
| | - Francesco Lotti
- Center for Motor Neuron Biology and Disease, Columbia University, New York, NY 10032, USA; Department of Pathology and Cell Biology, Columbia University, New York, NY 10032, USA
| | - Livio Pellizzoni
- Center for Motor Neuron Biology and Disease, Columbia University, New York, NY 10032, USA; Department of Pathology and Cell Biology, Columbia University, New York, NY 10032, USA.
| |
Collapse
|
21
|
Natalizio AH, Matera AG. Identification and characterization of Drosophila Snurportin reveals a role for the import receptor Moleskin/importin-7 in snRNP biogenesis. Mol Biol Cell 2013; 24:2932-42. [PMID: 23885126 PMCID: PMC3771954 DOI: 10.1091/mbc.e13-03-0118] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
Previous work established Importin-β and Snurportin1 as the vertebrate snRNP import receptor and adaptor proteins, respectively. This study identifies Drosophila Snurportin and shows that it uses an alternative import receptor, Importin7/Moleskin. Moleskin is required for the stability of other snRNP biogenesis factors. Nuclear import is an essential step in small nuclear ribonucleoprotein (snRNP) biogenesis. Snurportin1 (SPN1), the import adaptor, binds to trimethylguanosine (TMG) caps on spliceosomal small nuclear RNAs. Previous studies indicated that vertebrate snRNP import requires importin-β, the transport receptor that binds directly to SPN1. We identify CG42303/snup as the Drosophila orthologue of human snurportin1 (SNUPN). Of interest, the importin-β binding (IBB) domain of SPN1, which is essential for TMG cap–mediated snRNP import in humans, is not well conserved in flies. Consistent with its lack of an IBB domain, we find that Drosophila SNUP (dSNUP) does not interact with Ketel/importin-β. Fruit fly snRNPs also fail to bind Ketel; however, the importin-7 orthologue Moleskin (Msk) physically associates with both dSNUP and spliceosomal snRNPs and localizes to nuclear Cajal bodies. Strikingly, we find that msk-null mutants are depleted of the snRNP assembly factor, survival motor neuron, and the Cajal body marker, coilin. Consistent with a loss of snRNP import function, long-lived msk larvae show an accumulation of TMG cap signal in the cytoplasm. These data indicate that Ketel/importin-β does not play a significant role in Drosophila snRNP import and demonstrate a crucial function for Msk in snRNP biogenesis.
Collapse
Affiliation(s)
- Amanda Hicks Natalizio
- Curriculum in Genetics and Molecular Biology, University of North Carolina, Chapel Hill, NC 27599 Departments of Biology, University of North Carolina, Chapel Hill, NC 27599 Departments of Genetics, University of North Carolina, Chapel Hill, NC 27599 Program in Molecular Biology and Biotechnology, University of North Carolina, Chapel Hill, NC 27599 Lineberger Comprehensive Cancer Center, University of North Carolina, Chapel Hill, NC 27599
| | | |
Collapse
|
22
|
Piazzon N, Schlotter F, Lefebvre S, Dodré M, Méreau A, Soret J, Besse A, Barkats M, Bordonné R, Branlant C, Massenet S. Implication of the SMN complex in the biogenesis and steady state level of the signal recognition particle. Nucleic Acids Res 2012; 41:1255-72. [PMID: 23221635 PMCID: PMC3553995 DOI: 10.1093/nar/gks1224] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
Spinal muscular atrophy is a severe motor neuron disease caused by reduced levels of the ubiquitous Survival of MotoNeurons (SMN) protein. SMN is part of a complex that is essential for spliceosomal UsnRNP biogenesis. Signal recognition particle (SRP) is a ribonucleoprotein particle crucial for co-translational targeting of secretory and membrane proteins to the endoplasmic reticulum. SRP biogenesis is a nucleo-cytoplasmic multistep process in which the protein components, except SRP54, assemble with 7S RNA in the nucleolus. Then, SRP54 is incorporated after export of the pre-particle into the cytoplasm. The assembly factors necessary for SRP biogenesis remain to be identified. Here, we show that 7S RNA binds to purified SMN complexes in vitro and that SMN complexes associate with SRP in cellular extracts. We identified the RNA determinants required. Moreover, we report a specific reduction of 7S RNA levels in the spinal cord of SMN-deficient mice, and in a Schizosaccharomyces pombe strain carrying a temperature-degron allele of SMN. Additionally, microinjected antibodies directed against SMN or Gemin2 interfere with the association of SRP54 with 7S RNA in Xenopus laevis oocytes. Our data show that reduced levels of the SMN protein lead to defect in SRP steady-state level and describe the SMN complex as the first identified cellular factor required for SRP biogenesis.
Collapse
Affiliation(s)
- Nathalie Piazzon
- Laboratoire ARN-RNP structure-fonction-maturation, Enzymologie Moléculaire et Structurale (AREMS), Nancy Université-CNRS, UMR 7214, FR 3209, Faculté de Médecine de Nancy, BP 184, 9 avenue de la forêt de Haye, 54506 Vandoeuvre-les-Nancy Cedex, France
| | | | | | | | | | | | | | | | | | | | | |
Collapse
|
23
|
Interplay between polyadenylate-binding protein 1 and Kaposi's sarcoma-associated herpesvirus ORF57 in accumulation of polyadenylated nuclear RNA, a viral long noncoding RNA. J Virol 2012; 87:243-56. [PMID: 23077296 DOI: 10.1128/jvi.01693-12] [Citation(s) in RCA: 45] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023] Open
Abstract
Polyadenylate-binding protein cytoplasmic 1 (PABPC1) is a cytoplasmic-nuclear shuttling protein important for protein translation initiation and both RNA processing and stability. We report that PABPC1 forms a complex with the Kaposi's sarcoma-associated herpesvirus (KSHV) ORF57 protein, which allows ORF57 to interact with a 9-nucleotide (nt) core element of KSHV polyadenylated nuclear (PAN) RNA, a viral long noncoding RNA (lncRNA), and increase PAN stability. The N-terminal RNA recognition motifs (RRMs) of PABPC1 are necessary for the direct interaction with ORF57. During KSHV lytic infection, the expression of viral ORF57 leads to a substantial decrease in overall PABPC1 expression, along with a shift in the cellular distribution of the remaining PABPC1 to the nucleus. Interestingly, PABPC1 and ORF57 have opposing functions in modulating PAN steady-state accumulation. The suppressive effect of PABPC1 specific to PAN expression is alleviated by small interfering RNA knockdown of PABPC1 or by overexpression of ORF57. Conversely, ectopic PABPC1 reduces ORF57 steady-state protein levels and induces aberrant polyadenylation of PAN and thereby indirectly inhibits ORF57-mediated PAN accumulation. However, E1B-AP5 (heterogeneous nuclear ribonucleoprotein U-like 1), which interacts with a region outside the 9-nt core to stimulate PAN expression, does not interact or even colocalize with ORF57. Unlike PABPC1, the nuclear distribution of E1B-AP5 remains unchanged by viral lytic infection or overexpression of ORF57. Together, these data indicate that PABPC1 is an important cellular target of viral ORF57 to directly upregulate PAN accumulation during viral lytic infection, and the ability of host PABPC1 to disrupt ORF57 expression is a strategic host counterbalancing mechanism.
Collapse
|
24
|
Murina VN, Nikulin AD. RNA-binding Sm-like proteins of bacteria and archaea. similarity and difference in structure and function. BIOCHEMISTRY (MOSCOW) 2012; 76:1434-49. [PMID: 22339597 DOI: 10.1134/s0006297911130050] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
RNA-binding proteins play a significant role in many processes of RNA metabolism, such as splicing and processing, regulation of DNA transcription and RNA translation, etc. Among the great number of RNA-binding proteins, so-called RNA-chaperones occupy an individual niche; they were named for their ability to assist RNA molecules to gain their accurate native spatial structure. When binding with RNAs, they possess the capability of altering (melting) their secondary structure, thus providing a possibility for formation of necessary intramolecular contacts between individual RNA sites for proper folding. These proteins also have an additional helper function in RNA-RNA and RNA-protein interactions. Members of such class of the RNA-binding protein family are Sm and Sm-like proteins (Sm-Like, LSm). The presence of these proteins in bacteria, archaea, and eukaryotes emphasizes their biological significance. These proteins are now attractive for researchers because of their implication in many processes associated with RNAs in bacterial and archaeal cells. This review is focused on a comparison of architecture of bacterial and archaeal LSm proteins and their interaction with different RNA molecules.
Collapse
Affiliation(s)
- V N Murina
- Institute of Protein Research, Russian Academy of Sciences, Pushchino, Moscow Region, Russia
| | | |
Collapse
|
25
|
Human pathologies associated with defective RNA transport and localization in the nervous system. Biol Cell 2012; 99:649-61. [DOI: 10.1042/bc20070045] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
|
26
|
SMN deficiency attenuates migration of U87MG astroglioma cells through the activation of RhoA. Mol Cell Neurosci 2011; 49:282-9. [PMID: 22197680 DOI: 10.1016/j.mcn.2011.12.003] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2011] [Revised: 11/23/2011] [Accepted: 12/05/2011] [Indexed: 12/13/2022] Open
Abstract
Spinal muscular atrophy (SMA) is a neurodegenerative disease that affects alpha motoneurons in the spinal cord caused by homozygous deletion or specific mutations in the survival motoneuron-1 (SMN1) gene. Cell migration is critical at many stages of nervous system development; to investigate the role of SMN in cell migration, U87MG astroglioma cells were transduced with shSMN lentivectors and about 60% reduction in SMN expression was achieved. In a monolayer wound-healing assay, U87MG SMN-depleted cells exhibit reduced cell migration. In these cells, RhoA was activated and phosphorylated levels of myosin regulatory light chain (MLC), a substrate of the Rho kinase (ROCK), were found increased. The decrease in cell motility was related to activation of RhoA/Rho kinase (ROCK) signaling pathway as treatment with the ROCK inhibitor Y-27632 abrogated both the motility defects and MLC phosphorylation in SMN-depleted cells. As cell migration is regulated by continuous remodeling of the actin cytoskeleton, the actin distribution was studied in SMN-depleted cells. A shift from filamentous to monomeric (globular) actin, involving the disappearance of stress fibers, was observed. In addition, profilin I, an actin-sequestering protein showed an increased expression in SMN-depleted cells. SMN is known to physically interact with profilin, reducing its actin-sequestering activity. The present results suggest that in SMN-depleted cells, the increase in profilin I expression and the reduction in SMN inhibitory action on profilin could lead to reduced filamentous actin polymerization, thus decreasing cell motility. We propose that the alterations reported here in migratory activity in SMN-depleted cells, related to abnormal activation of RhoA/ROCK pathway and increased profilin I expression could have a role in developing nervous system by impairing normal neuron and glial cell migration and thus contributing to disease pathogenesis in SMA.
Collapse
|
27
|
Zhang R, So BR, Li P, Yong J, Glisovic T, Wan L, Dreyfuss G. Structure of a key intermediate of the SMN complex reveals Gemin2's crucial function in snRNP assembly. Cell 2011; 146:384-95. [PMID: 21816274 PMCID: PMC3160754 DOI: 10.1016/j.cell.2011.06.043] [Citation(s) in RCA: 83] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/19/2011] [Revised: 05/10/2011] [Accepted: 06/27/2011] [Indexed: 01/10/2023]
Abstract
The SMN complex mediates the assembly of heptameric Sm protein rings on small nuclear RNAs (snRNAs), which are essential for snRNP function. Specific Sm core assembly depends on Sm proteins and snRNA recognition by SMN/Gemin2- and Gemin5-containing subunits, respectively. The mechanism by which the Sm proteins are gathered while preventing illicit Sm assembly on non-snRNAs is unknown. Here, we describe the 2.5 Å crystal structure of Gemin2 bound to SmD1/D2/F/E/G pentamer and SMN's Gemin2-binding domain, a key assembly intermediate. Remarkably, through its extended conformation, Gemin2 wraps around the crescent-shaped pentamer, interacting with all five Sm proteins, and gripping its bottom and top sides and outer perimeter. Gemin2 reaches into the RNA-binding pocket, preventing RNA binding. Interestingly, SMN-Gemin2 interaction is abrogated by a spinal muscular atrophy (SMA)-causing mutation in an SMN helix that mediates Gemin2 binding. These findings provide insight into SMN complex assembly and specificity, linking snRNP biogenesis and SMA pathogenesis.
Collapse
Affiliation(s)
- Rundong Zhang
- Howard Hughes Medical Institute, University of Pennsylvania School of Medicine, Philadelphia, PA 19104-6148, USA
| | | | | | | | | | | | | |
Collapse
|
28
|
Fischer U, Englbrecht C, Chari A. Biogenesis of spliceosomal small nuclear ribonucleoproteins. WILEY INTERDISCIPLINARY REVIEWS-RNA 2011; 2:718-31. [PMID: 21823231 DOI: 10.1002/wrna.87] [Citation(s) in RCA: 109] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
Virtually, all eukaryotic mRNAs are synthesized as precursor molecules that need to be extensively processed in order to serve as a blueprint for proteins. The three most prevalent processing steps are the capping reaction at the 5'-end, the removal of intervening sequences by splicing, and the formation of poly (A)-tails at the 3'-end of the message by polyadenylation. A large number of proteins and small nuclear ribonucleoprotein complexes (snRNPs) interact with the mRNA and enable the different maturation steps. This chapter focuses on the biogenesis of snRNPs, the major components of the pre-mRNA splicing machinery (spliceosome). A large body of evidence has revealed an intricate and segmented pathway for the formation of snRNPs that involves nucleo-cytoplasmic transport events and elaborates assembly strategies. We summarize the knowledge about the different steps with an emphasis on trans-acting factors of snRNP maturation of higher eukaryotes. WIREs RNA 2011 2 718-731 DOI: 10.1002/wrna.87 For further resources related to this article, please visit the WIREs website.
Collapse
Affiliation(s)
- Utz Fischer
- Department of Biochemistry, University of Wuerzburg, Germany.
| | | | | |
Collapse
|
29
|
Eliana C, Javier E, Moisés W. Plasmodium falciparum spliceosomal RNAs: 3' and 5' end processing. Acta Trop 2011; 117:105-8. [PMID: 21093404 DOI: 10.1016/j.actatropica.2010.10.008] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/05/2010] [Revised: 10/10/2010] [Accepted: 10/20/2010] [Indexed: 11/27/2022]
Abstract
The major spliceosomal small nuclear ribonucleoproteins (snRNPs) consist of snRNA (U1, U2, U4 or U5) and several proteins which can be unique or common to each snRNP particle. The common proteins are known as Sm proteins; they are crucial for RNP assembly and nuclear import of spliceosomal RNPs. This paper reports detecting the interaction between Plasmodium falciparum snRNAs and Sm proteins, and the usual 5' trimethylated caps on the snRNAs, by immunoprecipitation with specific antibodies. Furthermore, an unusual poly(A) tail was detected on these non-coding RNAs.
Collapse
Affiliation(s)
- Calvo Eliana
- Universidad Nacional de Colombia, Facultad de Ciencias, Laboratorio de Investigaciones Básicas en Bioquímica, Bogotá Colombia
| | | | | |
Collapse
|
30
|
Zienkiewicz K, Suwinska A, Niedojadło K, Zienkiewicz A, Bednarska E. Nuclear activity of sperm cells during Hyacinthus orientalis L. in vitro pollen tube growth. JOURNAL OF EXPERIMENTAL BOTANY 2011; 62:1255-1269. [PMID: 21081664 PMCID: PMC3022407 DOI: 10.1093/jxb/erq354] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/29/2010] [Revised: 10/14/2010] [Accepted: 10/15/2010] [Indexed: 05/29/2023]
Abstract
In this study, the transcriptional state and distribution of RNA polymerase II, pre-mRNA splicing machinery elements, and rRNA transcripts were investigated in the sperm cells of Hyacinthus orientalis L. during in vitro pollen tube growth. During the second pollen mitosis, no nascent transcripts were observed in the area of the dividing generative cell, whereas the splicing factors were present and their pools were divided between newly formed sperm cells. Just after their origin, the sperm cells were shown to synthesize new RNA, although at a markedly lower level than the vegetative nucleus. The occurrence of RNA synthesis was accompanied by the presence of RNA polymerase II and a rich pool of splicing machinery elements. Differences in the spatial pattern of pre-mRNA splicing factors localization reflect different levels of RNA synthesis in the vegetative nucleus and sperm nuclei. In the vegetative nucleus, they were localized homogenously, whereas in the sperm nuclei a mainly speckled pattern of small nuclear RNA with a trimethylguanosine cap (TMG snRNA) and SC35 protein distribution was observed. As pollen tube growth proceeded, inhibition of RNA synthesis in the sperm nuclei was observed, which was accompanied by a gradual elimination of the splicing factors. In addition, analysis of rRNA localization indicated that the sperm nuclei are likely to synthesize some pool of rRNA at the later steps of pollen tube. It is proposed that the described changes in the nuclear activity of H. orientalis sperm cells reflect their maturation process during pollen tube growth, and that mature sperm cells do not carry into the zygote the nascent transcripts or the splicing machinery elements.
Collapse
Affiliation(s)
- Krzysztof Zienkiewicz
- Departamento de Bioquímica, Biología Celular y Molecular de Plantas, Estación Experimental del Zaidín CSIC, Profesor Albareda 1, 18008 Granada, Spain.
| | | | | | | | | |
Collapse
|
31
|
Mahmoudi S, Henriksson S, Weibrecht I, Smith S, Söderberg O, Strömblad S, Wiman KG, Farnebo M. WRAP53 is essential for Cajal body formation and for targeting the survival of motor neuron complex to Cajal bodies. PLoS Biol 2010; 8:e1000521. [PMID: 21072240 PMCID: PMC2970535 DOI: 10.1371/journal.pbio.1000521] [Citation(s) in RCA: 106] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2010] [Accepted: 09/03/2010] [Indexed: 02/02/2023] Open
Abstract
The WRAP53 gene gives rise to a p53 antisense transcript that regulates p53. This gene also encodes a protein that directs small Cajal body-specific RNAs to Cajal bodies. Cajal bodies are nuclear organelles involved in diverse functions such as processing ribonucleoproteins important for splicing. Here we identify the WRAP53 protein as an essential factor for Cajal body maintenance and for directing the survival of motor neuron (SMN) complex to Cajal bodies. By RNA interference and immunofluorescence we show that Cajal bodies collapse without WRAP53 and that new Cajal bodies cannot be formed. By immunoprecipitation we find that WRAP53 associates with the Cajal body marker coilin, the splicing regulatory protein SMN, and the nuclear import receptor importinβ, and that WRAP53 is essential for complex formation between SMN-coilin and SMN-importinβ. Furthermore, depletion of WRAP53 leads to accumulation of SMN in the cytoplasm and prevents the SMN complex from reaching Cajal bodies. Thus, WRAP53 mediates the interaction between SMN and associated proteins, which is important for nuclear targeting of SMN and the subsequent localization of the SMN complex to Cajal bodies. Moreover, we detect reduced WRAP53-SMN binding in patients with spinal muscular atrophy, which is the leading genetic cause of infant mortality worldwide, caused by mutations in SMN1. This suggests that loss of WRAP53-mediated SMN trafficking contributes to spinal muscular atrophy.
Collapse
Affiliation(s)
- Salah Mahmoudi
- Department of Oncology-Pathology, Cancer Centrum Karolinska, Karolinska Institutet, Stockholm, Sweden
| | - Sofia Henriksson
- Department of Oncology-Pathology, Cancer Centrum Karolinska, Karolinska Institutet, Stockholm, Sweden
| | - Irene Weibrecht
- Department of Genetics and Pathology, Rudbeck Laboratory, University of Uppsala, Uppsala, Sweden
| | - Stephen Smith
- Center for Biosciences, Department of Biosciences and Nutrition, Novum, Karolinska Institutet, Huddinge, Sweden
| | - Ola Söderberg
- Department of Genetics and Pathology, Rudbeck Laboratory, University of Uppsala, Uppsala, Sweden
| | - Staffan Strömblad
- Center for Biosciences, Department of Biosciences and Nutrition, Novum, Karolinska Institutet, Huddinge, Sweden
| | - Klas G. Wiman
- Department of Oncology-Pathology, Cancer Centrum Karolinska, Karolinska Institutet, Stockholm, Sweden
| | - Marianne Farnebo
- Department of Oncology-Pathology, Cancer Centrum Karolinska, Karolinska Institutet, Stockholm, Sweden
- * E-mail:
| |
Collapse
|
32
|
Gemin5 delivers snRNA precursors to the SMN complex for snRNP biogenesis. Mol Cell 2010; 38:551-62. [PMID: 20513430 PMCID: PMC2901871 DOI: 10.1016/j.molcel.2010.03.014] [Citation(s) in RCA: 99] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2009] [Revised: 02/16/2010] [Accepted: 03/26/2010] [Indexed: 12/26/2022]
Abstract
The SMN complex assembles Sm cores on snRNAs, a key step in the biogenesis of snRNPs, the spliceosome's major components. Here, using SMN complex inhibitors identified by high-throughput screening and a ribo-proteomic strategy on formaldehyde crosslinked RNPs, we dissected this pathway in cells. We show that protein synthesis inhibition impairs the SMN complex, revealing discrete SMN and Gemin subunits and accumulating an snRNA precursor (pre-snRNA)-Gemin5 intermediate. By high-throughput sequencing of this transient intermediate's RNAs, we discovered the previously undetectable precursors of all the snRNAs and identified their Gemin5-binding sites. We demonstrate that pre-snRNA 3' sequences function to enhance snRNP biogenesis. The SMN complex is also inhibited by oxidation, and we show that it stalls an inventory-complete SMN complex containing pre-snRNAs. We propose a stepwise pathway of SMN complex formation and snRNP biogenesis, highlighting Gemin5's function in delivering pre-snRNAs as substrates for Sm core assembly and processing.
Collapse
|
33
|
SMN and the Gemin proteins form sub-complexes that localise to both stationary and dynamic neurite granules. Biochem Biophys Res Commun 2010; 394:211-6. [PMID: 20188701 DOI: 10.1016/j.bbrc.2010.02.158] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2010] [Accepted: 02/23/2010] [Indexed: 11/21/2022]
Abstract
Childhood spinal muscular atrophy (SMA) is caused by a reduction in survival motor neuron (SMN) protein. SMN is expressed in every cell type, but it is predominantly the lower motor neurones of the spinal cord that degenerate in SMA. SMN has been linked to the axonal transport of beta-actin mRNA, a breakdown in which could trigger disease onset. It is known that SMN is present in transport ribonucleoproteins (RNPs) granules that also contain Gemin2 and Gemin3. To further characterise these granules we have performed live cell imaging of GFP-tagged SMN, GFP-Gemin2, GFP-Gemin3, GFP-Gemin6 and GFP-Gemin7. In all, we have made two important observations: (1) SMN granules appear metamorphic; and (2) the SMN-Gemin complex(es) appears to localise to two distinct subsets of bodies in neurites; stationary bodies and smaller dynamic bodies. This study provides an insight into the neuronal function of the SMN complex.
Collapse
|
34
|
Geib T, Hertel KJ. Restoration of full-length SMN promoted by adenoviral vectors expressing RNA antisense oligonucleotides embedded in U7 snRNAs. PLoS One 2009; 4:e8204. [PMID: 19997596 PMCID: PMC2781471 DOI: 10.1371/journal.pone.0008204] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/13/2009] [Accepted: 11/11/2009] [Indexed: 11/18/2022] Open
Abstract
Background Spinal Muscular Atrophy (SMA) is an autosomal recessive disease that leads to specific loss of motor neurons. It is caused by deletions or mutations of the survival of motor neuron 1 gene (SMN1). The remaining copy of the gene, SMN2, generates only low levels of the SMN protein due to a mutation in SMN2 exon 7 that leads to exon skipping. Methodology/Principal Findings To correct SMN2 splicing, we use Adenovirus type 5–derived vectors to express SMN2-antisense U7 snRNA oligonucleotides targeting the SMN intron 7/exon 8 junction. Infection of SMA type I–derived patient fibroblasts with these vectors resulted in increased levels of exon 7 inclusion, upregulating the expression of SMN to similar levels as in non–SMA control cells. Conclusions/Significance These results show that Adenovirus type 5–derived vectors delivering U7 antisense oligonucleotides can efficiently restore full-length SMN protein and suggest that the viral vector-mediated oligonucleotide application may be a suitable therapeutic approach to counteract SMA.
Collapse
Affiliation(s)
- Till Geib
- Department of Microbiology and Molecular Genetics, School of Medicine, University of California Irvine, Irvine, California, United States of America
| | - Klemens J. Hertel
- Department of Microbiology and Molecular Genetics, School of Medicine, University of California Irvine, Irvine, California, United States of America
- * E-mail:
| |
Collapse
|
35
|
Ogawa C, Usui K, Ito F, Itoh M, Hayashizaki Y, Suzuki H. Role of survival motor neuron complex components in small nuclear ribonucleoprotein assembly. J Biol Chem 2009; 284:14609-17. [PMID: 19321448 PMCID: PMC2682908 DOI: 10.1074/jbc.m809031200] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2008] [Revised: 03/19/2009] [Indexed: 11/06/2022] Open
Abstract
Survival motor neuron (SMN) complex is essential for the biogenesis of the small nuclear ribonucleoprotein (snRNP) complex, although the complete role of each SMN complex component for the snRNP synthesis is largely unclear. We have identified an interaction between the two components Gemin2-Gemin7 using the mammalian two-hybrid system. In vitro stability assay revealed that the known SMN-Gemin7 interaction becomes stable in the presence of Gemin2 possibly via the identified Gemin2-Gemin7 interaction. Gemin7 knockdown revealed a decrease in snRNP assembly activity and a decrease in SmE protein, a component of snRNP, in the SMN complex, which was consistent with a previous discussion that the Gemin6-Gemin7 heterodimer may serve as a surrogate for the SmD3-SmB particle in forming a subcore, the intermediate complex for snRNP. Interestingly, we found that Unrip, but not Gemin8, can remove Gemin7 from the stable SMN-Gemin2-Gemin7 ternary complex. In an in vitro snRNP assembly assay using the Unrip knockdown and the untreated cell lysates, we revealed that there was a decrease in Gemin7 and increase in SmB/B' in the SMN complex observed in untreated cells during the assay, suggesting that the Gemin6-Gemin7 heterodimer in the subcore is exchanged by the SmD3-SmB particle to form snRNP. Surprisingly, these changes were not observed in the assay using the Unrip knockdown cell extracts, indicating the importance of Unrip in the formation of snRNP likely via removal of the Gemin6-Gemin7 from the SMN complex. Taken together, these results indicate that snRNP is synthesized by harmonization of the SMN complex components.
Collapse
Affiliation(s)
- Chihiro Ogawa
- RIKEN Omics Sciences Center, RIKEN Yokohama Institute, Tsurumi-ku, Yokohama, Japan
| | | | | | | | | | | |
Collapse
|
36
|
Gemin5-snRNA interaction reveals an RNA binding function for WD repeat domains. Nat Struct Mol Biol 2009; 16:486-91. [PMID: 19377484 DOI: 10.1038/nsmb.1584] [Citation(s) in RCA: 82] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/03/2008] [Accepted: 03/06/2009] [Indexed: 11/09/2022]
Abstract
Gemin5 binds specifically to the small nuclear RNA (snRNA)-defining small nuclear ribonucleoprotein (snRNP) code sequence and is essential, together with other components of the survival of motor neurons (SMN) complex, for the biogenesis of snRNPs, the major constituents of spliceosomes. We show that this binding is mediated by Gemin5's WD repeat domain, a common domain not previously known to bind RNA independently. The entire WD repeat domain, comprising 13 WD motifs, is both necessary and sufficient for sequence-specific, high-affinity binding of Gemin5 to its RNA targets. Using an RNA-mediated hydroxyl radical probing method and mass spectrometry, we mapped a discrete region of the WD repeat domain that contacts snRNAs and demonstrated by mutagenesis that specific amino acids in this region are crucial for Gemin5-snRNA binding. The WD repeat domain is thus a previously undescribed RNA binding domain, and we suggest that the presence of WD repeats should be considered as predictive of potential function in RNA binding.
Collapse
|
37
|
Moreno PMD, Wenska M, Lundin KE, Wrange O, Strömberg R, Smith CIE. A synthetic snRNA m3G-CAP enhances nuclear delivery of exogenous proteins and nucleic acids. Nucleic Acids Res 2009; 37:1925-35. [PMID: 19208638 PMCID: PMC2665231 DOI: 10.1093/nar/gkp048] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022] Open
Abstract
Accessing the nucleus through the surrounding membrane poses one of the major obstacles for therapeutic molecules large enough to be excluded due to nuclear pore size limits. In some therapeutic applications the large size of some nucleic acids, like plasmid DNA, hampers their access to the nuclear compartment. However, also for small oligonucleotides, achieving higher nuclear concentrations could be of great benefit. We report on the synthesis and possible applications of a natural RNA 5′-end nuclear localization signal composed of a 2,2,7-trimethylguanosine cap (m3G-CAP). The cap is found in the small nuclear RNAs that are constitutive part of the small nuclear ribonucleoprotein complexes involved in nuclear splicing. We demonstrate the use of the m3G signal as an adaptor that can be attached to different oligonucleotides, thereby conferring nuclear targeting capabilities with capacity to transport large-size cargo molecules. The synthetic capping of oligos interfering with splicing may have immediate clinical applications.
Collapse
Affiliation(s)
- Pedro M D Moreno
- Department of Laboratory Medicine, Clinical Research Center, Karolinska Institutet, Karolinska University Hospital, SE-141 86 Huddinge, Sweden.
| | | | | | | | | | | |
Collapse
|
38
|
Joining the dots: Production, processing and targeting of U snRNP to nuclear bodies. BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR CELL RESEARCH 2008; 1783:2137-44. [DOI: 10.1016/j.bbamcr.2008.07.025] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/08/2008] [Revised: 07/22/2008] [Accepted: 07/23/2008] [Indexed: 11/20/2022]
|
39
|
Walker MP, Rajendra TK, Saieva L, Fuentes JL, Pellizzoni L, Matera AG. SMN complex localizes to the sarcomeric Z-disc and is a proteolytic target of calpain. Hum Mol Genet 2008; 17:3399-410. [PMID: 18689355 DOI: 10.1093/hmg/ddn234] [Citation(s) in RCA: 70] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Spinal muscular atrophy (SMA) is a recessive neuromuscular disease caused by mutations in the human survival motor neuron 1 (SMN1) gene. The human SMN protein is part of a large macromolecular complex involved in the biogenesis of small ribonucleoproteins. Previously, we showed that SMN is a sarcomeric protein in flies and mice. In this report, we show that the entire mouse Smn complex localizes to the sarcomeric Z-disc. Smn colocalizes with alpha-actinin, a Z-disc marker protein, in both skeletal and cardiac myofibrils. Furthermore, this localization is both calcium- and calpain-dependent. Calpains are known to release proteins from various regions of the sarcomere as a part of the normal functioning of the muscle; however, this removal can be either direct or indirect. Using mammalian cell lysates, purified native SMN complexes, as well as recombinant SMN protein, we show that SMN is a direct target of calpain cleavage. Finally, myofibers from a mouse model of severe SMA, but not controls, display morphological defects that are consistent with a Z-disc deficiency. These results support the view that the SMN complex performs a muscle-specific function at the Z-discs.
Collapse
Affiliation(s)
- Michael P Walker
- Department of Genetics, School of Medicine, Case Western Reserve University, Cleveland, OH 44106-4955, USA
| | | | | | | | | | | |
Collapse
|
40
|
|
41
|
Minor spliceosome components are predominantly localized in the nucleus. Proc Natl Acad Sci U S A 2008; 105:8655-60. [PMID: 18559850 DOI: 10.1073/pnas.0803646105] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Recently, it has been reported that there is a differential subcellular distribution of components of the minor U12-dependent and major U2-dependent spliceosome, and further that the minor spliceosome functions in the cytoplasm. To study the subcellular localization of the snRNA components of both the major and minor spliceosomes, we performed in situ hybridizations with mouse tissues and human cells. In both cases, all spliceosomal snRNAs were nearly exclusively detected in the nucleus, and the minor U11 and U12 snRNAs were further shown to colocalize with U4 and U2, respectively, in human cells. Additionally, we examined the distribution of several spliceosomal snRNAs and proteins in nuclear and cytoplasmic fractions isolated from human cells. These studies revealed an identical subcellular distribution of components of both the U12- and U2-dependent spliceosomes. Thus, our data, combined with several earlier publications, establish that, like the major spliceosome, components of the U12-dependent spliceosome are localized predominantly in the nucleus.
Collapse
|
42
|
Mouillet JF, Yan X, Ou Q, Jin L, Muglia LJ, Crawford PA, Sadovsky Y. DEAD-box protein-103 (DP103, Ddx20) is essential for early embryonic development and modulates ovarian morphology and function. Endocrinology 2008; 149:2168-75. [PMID: 18258677 PMCID: PMC2329271 DOI: 10.1210/en.2007-1237] [Citation(s) in RCA: 49] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
The DEAD-box helicase DP103 (Ddx20, Gemin3) is a multifunctional protein that interacts with Epstein-Barr virus nuclear proteins (EBNA2/EBNA3) and is a part of the spliceosomal small nuclear ribonucleoproteins complex. DP103 also aggregates with the micro-RNA machinery complex. We have previously shown that DP103 interacts with the nuclear receptor steroidogenic factor-1 (SF-1, NR5A1), a key regulator of reproductive development, and represses its transcriptional activity. To further explore the physiological function of DP103, we disrupted the corresponding gene in mice. Homozygous Dp103-null mice die early in embryonic development before a four-cell stage. Although heterozygous mice are healthy and fertile, analysis of steroidogenic tissues revealed minor abnormalities in mutant females, including larger ovaries, altered estrous cycle, and reduced basal secretion of ACTH. Our data point to diverse functions of murine DP103, with an obligatory role during early embryonic development and also in modulation of steroidogenesis.
Collapse
Affiliation(s)
- Jean-François Mouillet
- Department of Obstetrics and Gynecology, Washington University School of Medicine, St. Louis, Missouri 63110, USA
| | | | | | | | | | | | | |
Collapse
|
43
|
Piazzon N, Rage F, Schlotter F, Moine H, Branlant C, Massenet S. In vitro and in cellulo evidences for association of the survival of motor neuron complex with the fragile X mental retardation protein. J Biol Chem 2007; 283:5598-610. [PMID: 18093976 DOI: 10.1074/jbc.m707304200] [Citation(s) in RCA: 76] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Spinal muscular atrophy (SMA) is caused by reduced levels of the survival of motor neuron (SMN) protein. Although the SMN complex is essential for assembly of spliceosomal U small nuclear RNPs, it is still not understood why reduced levels of the SMN protein specifically cause motor neuron degeneration. SMN was recently proposed to have specific functions in mRNA transport and translation regulation in neuronal processes. The defective protein in Fragile X mental retardation syndrome (FMRP) also plays a role in transport of mRNPs and in their translation. Therefore, we examined possible relationships of SMN with FMRP. We observed granules containing both transiently expressed red fluorescent protein(RFP)-tagged SMN and green fluorescent protein(GFP)-tagged FMRP in cell bodies and processes of rat primary neurons of hypothalamus in culture. By immunoprecipitation experiments, we detected an association of FMRP with the SMN complex in human neuroblastoma SH-SY5Y cells and in murine motor neuron MN-1 cells. Then, by in vitro experiments, we demonstrated that the SMN protein is essential for this association. We showed that the COOH-terminal region of FMRP, as well as the conserved YG box and the region encoded by exon 7 of SMN, are required for the interaction. Our findings suggest a link between the SMN complex and FMRP in neuronal cells.
Collapse
Affiliation(s)
- Nathalie Piazzon
- Laboratoire de Maturation des ARN et Enzymologie Moléculaire, UMR 7567 CNRS-UHP Nancy I, Faculté des Sciences, BP 239, 54506 Vandoeuvre-les-Nancy Cedex
| | | | | | | | | | | |
Collapse
|
44
|
Gabanella F, Butchbach MER, Saieva L, Carissimi C, Burghes AHM, Pellizzoni L. Ribonucleoprotein assembly defects correlate with spinal muscular atrophy severity and preferentially affect a subset of spliceosomal snRNPs. PLoS One 2007; 2:e921. [PMID: 17895963 PMCID: PMC1976558 DOI: 10.1371/journal.pone.0000921] [Citation(s) in RCA: 252] [Impact Index Per Article: 14.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/14/2007] [Accepted: 09/07/2007] [Indexed: 11/18/2022] Open
Abstract
Spinal muscular atrophy (SMA) is a motor neuron disease caused by reduced levels of the survival motor neuron (SMN) protein. SMN together with Gemins2-8 and unrip proteins form a macromolecular complex that functions in the assembly of small nuclear ribonucleoproteins (snRNPs) of both the major and the minor splicing pathways. It is not known whether the levels of spliceosomal snRNPs are decreased in SMA. Here we analyzed the consequence of SMN deficiency on snRNP metabolism in the spinal cord of mouse models of SMA with differing phenotypic severities. We demonstrate that the expression of a subset of Gemin proteins and snRNP assembly activity are dramatically reduced in the spinal cord of severe SMA mice. Comparative analysis of different tissues highlights a similar decrease in SMN levels and a strong impairment of snRNP assembly in tissues of severe SMA mice, although the defect appears smaller in kidney than in neural tissue. We further show that the extent of reduction in both Gemin proteins expression and snRNP assembly activity in the spinal cord of SMA mice correlates with disease severity. Remarkably, defective SMN complex function in snRNP assembly causes a significant decrease in the levels of a subset of snRNPs and preferentially affects the accumulation of U11 snRNP--a component of the minor spliceosome--in tissues of severe SMA mice. Thus, impairment of a ubiquitous function of SMN changes the snRNP profile of SMA tissues by unevenly altering the normal proportion of endogenous snRNPs. These findings are consistent with the hypothesis that SMN deficiency affects the splicing machinery and in particular the minor splicing pathway of a rare class of introns in SMA.
Collapse
Affiliation(s)
- Francesca Gabanella
- Dulbecco Telethon Institute, Institute of Cell Biology, Monterotondo Scalo, Rome, Italy
| | - Matthew E. R. Butchbach
- Department of Molecular and Cellular Biochemistry, Ohio State University, Columbus, Ohio, United States of America
| | - Luciano Saieva
- Dulbecco Telethon Institute, Institute of Cell Biology, Monterotondo Scalo, Rome, Italy
- Center for Motor Neuron Biology and Disease, Department of Pathology, Columbia University Medical Center, New York, New York, United States of America
| | - Claudia Carissimi
- Dulbecco Telethon Institute, Institute of Cell Biology, Monterotondo Scalo, Rome, Italy
| | - Arthur H. M. Burghes
- Department of Molecular and Cellular Biochemistry, Ohio State University, Columbus, Ohio, United States of America
| | - Livio Pellizzoni
- Dulbecco Telethon Institute, Institute of Cell Biology, Monterotondo Scalo, Rome, Italy
- Center for Motor Neuron Biology and Disease, Department of Pathology, Columbia University Medical Center, New York, New York, United States of America
- * To whom correspondence should be addressed. E-mail:
| |
Collapse
|
45
|
Battle DJ, Kasim M, Wang J, Dreyfuss G. SMN-independent subunits of the SMN complex. Identification of a small nuclear ribonucleoprotein assembly intermediate. J Biol Chem 2007; 282:27953-9. [PMID: 17640873 DOI: 10.1074/jbc.m702317200] [Citation(s) in RCA: 50] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The survival of motor neurons (SMN) complex is essential for the biogenesis of small nuclear ribonucleoprotein (snRNP) complexes in eukaryotic cells. Reduced levels of SMN cause the motor neuron degenerative disease, spinal muscular atrophy. We identify here stable subunits of the SMN complex that do not contain SMN. Sedimentation and immunoprecipitation experiments using cell extracts reveal at least three complexes composed of Gemin3, -4, and -5; Gemin6, -7, and unrip; and SMN with Gemin2, as well as free Gemin5. Complexes containing Gemin3-Gemin4-Gemin5 and Gemin6-Gemin7-unrip persist at similar levels when SMN is reduced. In cells, immunofluorescence microscopy shows differential localization of Gemin5 after cell stress. We further show that the Gemin5-containing subunits bind small nuclear RNA independently of the SMN complex and without a requirement for exogenous ATP. ATP hydrolysis is, however, required for displacement of small nuclear RNAs from the Gemin5-containing subunits and their assembly into snRNPs. These findings demonstrate a modular nature of the SMN complex and identify a new intermediate in the snRNP assembly process.
Collapse
Affiliation(s)
- Daniel J Battle
- Howard Hughes Medical Institute and Department of Biochemistry and Biophysics, University of Pennsylvania School of Medicine, Philadelphia, Pennsylvania 19104-6148, USA
| | | | | | | |
Collapse
|
46
|
Abstract
It has been proposed that defects in the assembly of spliceosomal uridine-rich small nuclear ribonucleoprotein (U snRNP) complexes could account for the death of motor neurons in spinal muscular atrophy (SMA). We discovered that infection of cultured cells with poliovirus results in the specific cleavage of the host factor Gemin3 by a virus-encoded proteinase, 2A(pro). Gemin3 is a component of the macromolecular SMN complex that mediates assembly of U snRNP complexes by aiding the heptameric oligomerization of Sm proteins onto U snRNAs. Using in vitro Sm core assembly assays, we found that lowering the intracellular amounts of Gemin3 by either poliovirus infection or small interfering RNA (siRNA)-mediated knockdown of Gemin3 resulted in reduced assembly of U snRNPs. Immunofluorescence analyses revealed a specific redistribution of Sm proteins from the nucleoplasm to the cytoplasmic periphery of the nucleus in poliovirus-infected cells. We propose that defects in U snRNP assembly may be shared features of SMA and poliomyelitis.
Collapse
Affiliation(s)
- Laura L. Almstead
- Department of Microbiology and Immunology, Stanford University School of Medicine, Stanford, California 94305, USA
| | - Peter Sarnow
- Department of Microbiology and Immunology, Stanford University School of Medicine, Stanford, California 94305, USA
- Corresponding author.E-MAIL ; FAX (650) 498-7147
| |
Collapse
|
47
|
Reiche K, Stadler PF. RNAstrand: reading direction of structured RNAs in multiple sequence alignments. Algorithms Mol Biol 2007; 2:6. [PMID: 17540014 PMCID: PMC1892782 DOI: 10.1186/1748-7188-2-6] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2007] [Accepted: 05/31/2007] [Indexed: 11/10/2022] Open
Abstract
MOTIVATION Genome-wide screens for structured ncRNA genes in mammals, urochordates, and nematodes have predicted thousands of putative ncRNA genes and other structured RNA motifs. A prerequisite for their functional annotation is to determine the reading direction with high precision. RESULTS While folding energies of an RNA and its reverse complement are similar, the differences are sufficient at least in conjunction with substitution patterns to discriminate between structured RNAs and their complements. We present here a support vector machine that reliably classifies the reading direction of a structured RNA from a multiple sequence alignment and provides a considerable improvement in classification accuracy over previous approaches. SOFTWARE RNAstrand is freely available as a stand-alone tool from http://www.bioinf.uni-leipzig.de/Software/RNAstrand and is also included in the latest release of RNAz, a part of the Vienna RNA Package.
Collapse
Affiliation(s)
- Kristin Reiche
- Bioinformatics Group, Dept. of Computer Science, and Interdisciplinary Center for Bioinformatics, University of Leipzig, Härtelstraße 16-18, D-04107 Leipzig, Germany
| | - Peter F Stadler
- Bioinformatics Group, Dept. of Computer Science, and Interdisciplinary Center for Bioinformatics, University of Leipzig, Härtelstraße 16-18, D-04107 Leipzig, Germany
- Institute for Theoretical Chemistry, University of Vienna, Währingerstraße 17, A-1090 Wien, Austria
- Santa Fe Institute, 1399 Hyde Park Rd., Santa Fe, NM 87501, USA
| |
Collapse
|
48
|
Pellizzoni L. Chaperoning ribonucleoprotein biogenesis in health and disease. EMBO Rep 2007; 8:340-5. [PMID: 17401408 PMCID: PMC1852756 DOI: 10.1038/sj.embor.7400941] [Citation(s) in RCA: 132] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2006] [Accepted: 01/31/2007] [Indexed: 12/11/2022] Open
Abstract
The survival motor neuron (SMN) protein is part of a macromolecular complex that functions in the biogenesis of small nuclear ribonucleoproteins (snRNPs)--the essential components of the pre-messenger RNA splicing machinery--as well as probably other RNPs. Reduced levels of SMN expression cause the inherited motor neuron disease spinal muscular atrophy (SMA). Knowledge of the composition, interactions and functions of the SMN complex has advanced greatly in recent years. The emerging picture is that the SMN complex acts as a macromolecular chaperone of RNPs to increase the efficiency and fidelity of RNA-protein interactions in vivo, and to provide an opportunity for these interactions to be regulated. In addition, it seems that RNA metabolism deficiencies underlie SMA. Here, a dual dysfunction hypothesis is presented in which two mechanistically and temporally distinct defects--that are dependent on the extent of SMN reduction in SMA--affect the homeostasis of specific messenger RNAs encoding proteins essential for motor neuron development and function.
Collapse
Affiliation(s)
- Livio Pellizzoni
- Dulbecco Telethon Institute, Institute of Cell Biology (CNR), Via E. Ramarini 32, 00016 Monterotondo Scalo, Rome, Italy.
| |
Collapse
|
49
|
Gangwani L. Deficiency of the zinc finger protein ZPR1 causes defects in transcription and cell cycle progression. J Biol Chem 2006; 281:40330-40. [PMID: 17068332 DOI: 10.1074/jbc.m608165200] [Citation(s) in RCA: 42] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The zinc finger protein ZPR1 is present in both the cytoplasm and nucleoplasm. Cell cycle analysis demonstrates that ZPR1 undergoes major changes in subcellular distribution during proliferation. ZPR1 is diffusely localized throughout the cell during the G(1) and G(2)/M phases of the cell cycle. In contrast, ZPR1 redistributes to the nucleus during S phase and ZPR1 exhibits prominent co-localization with the survival motor neurons protein and the histone gene-specific transcription factor NPAT in subnuclear foci, including Cajal bodies that associate with histone gene clusters. ZPR1 deficiency causes disruption of survival motor neurons and NPAT localization within the nucleus, blocks S phase progression, and arrests cells in both the G(1) and G(2) phases of the cell cycle. These changes in subnuclear architecture and cell cycle progression may be caused by transcriptional defects in ZPR1-deficient cells, including decreased histone gene expression.
Collapse
Affiliation(s)
- Laxman Gangwani
- Program in Molecular Medicine, University of Massachusetts Medical School, Worcester, Massachusetts 01605, USA.
| |
Collapse
|
50
|
Battle DJ, Lau CK, Wan L, Deng H, Lotti F, Dreyfuss G. The Gemin5 protein of the SMN complex identifies snRNAs. Mol Cell 2006; 23:273-9. [PMID: 16857593 DOI: 10.1016/j.molcel.2006.05.036] [Citation(s) in RCA: 127] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2006] [Revised: 05/16/2006] [Accepted: 05/23/2006] [Indexed: 10/24/2022]
Abstract
The survival of motor neurons protein (SMN) is part of a large complex that contains six other proteins, Gemins2-7. The SMN complex assembles the heptameric Sm protein core on small nuclear RNAs (snRNAs) and plays a critical role in the biogenesis of snRNPs, the major and essential components of mRNA splicing in eukaryotes. For its function, the SMN complex binds Sm proteins and snRNAs, which it distinguishes from other RNAs by specific features they contain. We show here that Gemin5, a 170 kDa WD-repeat protein, is the snRNA binding protein of the SMN complex. Gemin5 binds directly and specifically to the unique features, including the Sm site, of snRNAs. Reduction of Gemin5 results in reduced capacity of the SMN complex to bind snRNAs and to assemble Sm cores. Gemin5 therefore functions as the factor that allows the SMN complex to distinguish snRNAs from other cellular RNAs for snRNP biogenesis.
Collapse
Affiliation(s)
- Daniel J Battle
- Howard Hughes Medical Institute, University of Pennsylvania School of Medicine, Philadelphia, Pennsylvania 19104, USA
| | | | | | | | | | | |
Collapse
|