1
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Bensaude O, Barbosa I, Morillo L, Dikstein R, Le Hir H. Exon-junction complex association with stalled ribosomes and slow translation-independent disassembly. Nat Commun 2024; 15:4209. [PMID: 38760352 PMCID: PMC11101648 DOI: 10.1038/s41467-024-48371-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/05/2023] [Accepted: 04/29/2024] [Indexed: 05/19/2024] Open
Abstract
Exon junction complexes are deposited at exon-exon junctions during splicing. They are primarily known to activate non-sense mediated degradation of transcripts harbouring premature stop codons before the last intron. According to a popular model, exon-junction complexes accompany mRNAs to the cytoplasm where the first translating ribosome pushes them out. However, they are also removed by uncharacterized, translation-independent mechanisms. Little is known about kinetic and transcript specificity of these processes. Here we tag core subunits of exon-junction complexes with complementary split nanoluciferase fragments to obtain sensitive and quantitative assays for complex formation. Unexpectedly, exon-junction complexes form large stable mRNPs containing stalled ribosomes. Complex assembly and disassembly rates are determined after an arrest in transcription and/or translation. 85% of newly deposited exon-junction complexes are disassembled by a translation-dependent mechanism. However as this process is much faster than the translation-independent one, only 30% of the exon-junction complexes present in cells at steady state require translation for disassembly. Deep RNA sequencing shows a bias of exon-junction complex bound transcripts towards microtubule and centrosome coding ones and demonstrate that the lifetimes of exon-junction complexes are transcript-specific. This study provides a dynamic vision of exon-junction complexes and uncovers their unexpected stable association with ribosomes.
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Affiliation(s)
- Olivier Bensaude
- Institut de Biologie de l'Ecole Normale Supérieure (IBENS), Ecole Normale Supérieure, CNRS, INSERM, PSL Research University, Paris, France.
| | - Isabelle Barbosa
- Institut de Biologie de l'Ecole Normale Supérieure (IBENS), Ecole Normale Supérieure, CNRS, INSERM, PSL Research University, Paris, France
| | - Lucia Morillo
- Institut de Biologie de l'Ecole Normale Supérieure (IBENS), Ecole Normale Supérieure, CNRS, INSERM, PSL Research University, Paris, France
| | - Rivka Dikstein
- Department of Biomolecular Sciences, The Weizmann Institute of Science, Rehovot, Israel
| | - Hervé Le Hir
- Institut de Biologie de l'Ecole Normale Supérieure (IBENS), Ecole Normale Supérieure, CNRS, INSERM, PSL Research University, Paris, France.
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2
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Morillo L, Paternina T, Alasseur Q, Genovesio A, Schwartz S, Le Hir H. Comprehensive mapping of exon junction complex binding sites reveals universal EJC deposition in Drosophila. BMC Biol 2023; 21:246. [PMID: 37936138 PMCID: PMC10630996 DOI: 10.1186/s12915-023-01749-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2023] [Accepted: 10/26/2023] [Indexed: 11/09/2023] Open
Abstract
BACKGROUND The exon junction complex (EJC) is involved in most steps of the mRNA life cycle, ranging from splicing to nonsense-mediated mRNA decay (NMD). It is assembled by the splicing machinery onto mRNA in a sequence-independent manner. A fundamental open question is whether the EJC is deposited onto all exon‒exon junctions or only on a subset of them. Several previous studies have made observations supportive of the latter, yet these have been limited by methodological constraints. RESULTS In this study, we sought to overcome these limitations via the integration of two different approaches for transcriptome-wide mapping of EJCs. Our results revealed that nearly all, if not all, internal exons consistently harbor an EJC in Drosophila, demonstrating that EJC presence is an inherent consequence of the splicing reaction. Furthermore, our study underscores the limitations of eCLIP methods in fully elucidating the landscape of RBP binding sites. Our findings highlight how highly specific (low false positive) methodologies can lead to erroneous interpretations due to partial sensitivity (high false negatives). CONCLUSIONS This study contributes to our understanding of EJC deposition and its association with pre-mRNA splicing. The universal presence of EJC on internal exons underscores its significance in ensuring proper mRNA processing. Additionally, our observations highlight the need to consider both specificity and sensitivity in RBP mapping methodologies.
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Affiliation(s)
- Lucía Morillo
- Institut de Biologie de l'École Normale Supérieure (IBENS), École Normale Supérieure, CNRS, INSERM, Université PSL, Paris, 75005, France
| | - Toni Paternina
- Institut de Biologie de l'École Normale Supérieure (IBENS), École Normale Supérieure, CNRS, INSERM, Université PSL, Paris, 75005, France
| | - Quentin Alasseur
- Institut de Biologie de l'École Normale Supérieure (IBENS), École Normale Supérieure, CNRS, INSERM, Université PSL, Paris, 75005, France
| | - Auguste Genovesio
- Institut de Biologie de l'École Normale Supérieure (IBENS), École Normale Supérieure, CNRS, INSERM, Université PSL, Paris, 75005, France
| | - Schraga Schwartz
- Department of Molecular Genetics, Weizmann Institute of Science, Rehovot, 7630031, Israel
| | - Hervé Le Hir
- Institut de Biologie de l'École Normale Supérieure (IBENS), École Normale Supérieure, CNRS, INSERM, Université PSL, Paris, 75005, France.
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3
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Bensidoun P, Zenklusen D, Oeffinger M. Differential affinity purification and mass spectrometry analysis of two nuclear pore complex isoforms in yeast S. cerevisiae. STAR Protoc 2023; 4:102359. [PMID: 37327111 PMCID: PMC10300402 DOI: 10.1016/j.xpro.2023.102359] [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: 01/31/2023] [Revised: 04/03/2023] [Accepted: 05/16/2023] [Indexed: 06/18/2023] Open
Abstract
Two isoforms of the nuclear pore complex (NPC) have been identified in the yeast S. cerevisiae, which coexist at the periphery of the nucleus and differ by the presence or absence of a nuclear basket. Here, we present a protocol to isolate the two types of NPCs from the same cell extract and dissect their interactomes. We describe steps for powder preparation and magnetic bead conjunction and detail differential affinity purification and outcome evaluation through SDS-PAGE, silver staining, and mass spectrometry analysis. For complete details on the use and execution of this protocol, please refer to Bensidoun et al.1.
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Affiliation(s)
- Pierre Bensidoun
- Institut de Recherches Cliniques de Montréal, 110 Avenue des Pins Ouest, Montréal, QC H2W 1R7, Canada; Département de Biochimie et Médecine Moléculaire, Faculté de Médecine, Université de Montréal, Montréal, QC H3T 1J4, Canada
| | - Daniel Zenklusen
- Département de Biochimie et Médecine Moléculaire, Faculté de Médecine, Université de Montréal, Montréal, QC H3T 1J4, Canada.
| | - Marlene Oeffinger
- Institut de Recherches Cliniques de Montréal, 110 Avenue des Pins Ouest, Montréal, QC H2W 1R7, Canada; Département de Biochimie et Médecine Moléculaire, Faculté de Médecine, Université de Montréal, Montréal, QC H3T 1J4, Canada; Faculty of Medicine, Division of Experimental Medicine, McGill University, Montréal, QC H3A 1A3, Canada.
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4
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Jalloh B, Lancaster CL, Rounds JC, Brown BE, Leung SW, Banerjee A, Morton DJ, Bienkowski RS, Fasken MB, Kremsky IJ, Tegowski M, Meyer K, Corbett A, Moberg K. The Drosophila Nab2 RNA binding protein inhibits m 6A methylation and male-specific splicing of Sex lethal transcript in female neuronal tissue. eLife 2023; 12:e64904. [PMID: 37458420 PMCID: PMC10351920 DOI: 10.7554/elife.64904] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2020] [Accepted: 06/23/2023] [Indexed: 07/20/2023] Open
Abstract
The Drosophila polyadenosine RNA binding protein Nab2, which is orthologous to a human protein lost in a form of inherited intellectual disability, controls adult locomotion, axon projection, dendritic arborization, and memory through a largely undefined set of target RNAs. Here, we show a specific role for Nab2 in regulating splicing of ~150 exons/introns in the head transcriptome and focus on retention of a male-specific exon in the sex determination factor Sex-lethal (Sxl) that is enriched in female neurons. Previous studies have revealed that this splicing event is regulated in females by N6-methyladenosine (m6A) modification by the Mettl3 complex. At a molecular level, Nab2 associates with Sxl pre-mRNA in neurons and limits Sxl m6A methylation at specific sites. In parallel, reducing expression of the Mettl3, Mettl3 complex components, or the m6A reader Ythdc1 rescues mutant phenotypes in Nab2 flies. Overall, these data identify Nab2 as an inhibitor of m6A methylation and imply significant overlap between Nab2 and Mettl3 regulated RNAs in neuronal tissue.
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Affiliation(s)
- Binta Jalloh
- Department of Biology, Emory UniversityAtlantaUnited States
- Department of Cell Biology Emory University School of MedicineAtlantaUnited States
- Graduate Program in Genetics and Molecular Biology, Emory UniversityAtlantaUnited States
| | - Carly L Lancaster
- Department of Biology, Emory UniversityAtlantaUnited States
- Department of Cell Biology Emory University School of MedicineAtlantaUnited States
- Graduate Program in Biochemistry, Cell and Developmental Biology, Emory UniversityAtlantaUnited States
| | - J Christopher Rounds
- Department of Biology, Emory UniversityAtlantaUnited States
- Department of Cell Biology Emory University School of MedicineAtlantaUnited States
- Graduate Program in Genetics and Molecular Biology, Emory UniversityAtlantaUnited States
| | - Brianna E Brown
- Department of Biology, Emory UniversityAtlantaUnited States
- Department of Cell Biology Emory University School of MedicineAtlantaUnited States
| | - Sara W Leung
- Department of Biology, Emory UniversityAtlantaUnited States
| | - Ayan Banerjee
- Department of Biology, Emory UniversityAtlantaUnited States
| | - Derrick J Morton
- Department of Biology, Emory UniversityAtlantaUnited States
- Emory Institutional Research and Academic Career Development Award (IRACDA), Fellowships in Research and Science Teaching (FIRST) Postdoctoral FellowshipAtlantaUnited States
| | - Rick S Bienkowski
- Department of Biology, Emory UniversityAtlantaUnited States
- Department of Cell Biology Emory University School of MedicineAtlantaUnited States
- Graduate Program in Genetics and Molecular Biology, Emory UniversityAtlantaUnited States
| | - Milo B Fasken
- Department of Biology, Emory UniversityAtlantaUnited States
| | | | - Matthew Tegowski
- Department of Biochemistry, Duke University School of MedicineDurhamUnited States
| | - Kate Meyer
- Department of Biochemistry, Duke University School of MedicineDurhamUnited States
- Department of Neurobiology, Duke University School of MedicineDurhamUnited States
| | - Anita Corbett
- Department of Biology, Emory UniversityAtlantaUnited States
| | - Ken Moberg
- Department of Cell Biology Emory University School of MedicineAtlantaUnited States
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5
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McSweeney C, Chen M, Dong F, Sebastian A, Reynolds DJ, Mott J, Pei Z, Zou J, Shi Y, Mao Y. Transcriptomic Analyses of Brains of RBM8A Conditional Knockout Mice at Different Developmental Stages Reveal Conserved Signaling Pathways Contributing to Neurodevelopmental Diseases. Int J Mol Sci 2023; 24:4600. [PMID: 36902031 PMCID: PMC10003467 DOI: 10.3390/ijms24054600] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/31/2022] [Revised: 02/20/2023] [Accepted: 02/22/2023] [Indexed: 03/03/2023] Open
Abstract
RNA-binding motif 8A (RBM8A) is a core component of the exon junction complex (EJC) that binds pre-mRNAs and regulates their splicing, transport, translation, and nonsense-mediated decay (NMD). Dysfunction in the core proteins has been linked to several detriments in brain development and neuropsychiatric diseases. To understand the functional role of Rbm8a in brain development, we have generated brain-specific Rbm8a knockout mice and used next-generation RNA-sequencing to identify differentially expressed genes (DEGs) in mice with heterozygous, conditional knockout (cKO) of Rbm8a in the brain at postnatal day 17 (P17) and at embryonic day 12. Additionally, we analyzed enriched gene clusters and signaling pathways within the DEGs. At the P17 time point, between the control and cKO mice, about 251 significant DEGs were identified. At E12, only 25 DEGs were identified in the hindbrain samples. Bioinformatics analyses have revealed many signaling pathways related to the central nervous system (CNS). When E12 and P17 results were compared, three DEGs, Spp1, Gpnmb, and Top2a, appeared to peak at different developmental time points in the Rbm8a cKO mice. Enrichment analyses suggested altered activity in pathways affecting cellular proliferation, differentiation, and survival. The results support the hypothesis that loss of Rbm8a causes decreased cellular proliferation, increased apoptosis, and early differentiation of neuronal subtypes, which may lead ultimately to an altered neuronal subtype composition in the brain.
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Affiliation(s)
- Colleen McSweeney
- Department of Biology, Pennsylvania State University, University Park, PA 16802, USA
| | - Miranda Chen
- Department of Biology, Pennsylvania State University, University Park, PA 16802, USA
| | - Fengping Dong
- Department of Biology, Pennsylvania State University, University Park, PA 16802, USA
- Department of Genetics, Washington University School of Medicine, St. Louis, MO 63110, USA
| | - Aswathy Sebastian
- Department of Biochemistry and Molecular Biology, Pennsylvania State University, University Park, PA 16802, USA
| | - Derrick James Reynolds
- Department of Microbiology & Molecular Genetics, School of Medicine, University of California, Irvine, CA 92697, USA
| | - Jennifer Mott
- Department of Biology, Pennsylvania State University, University Park, PA 16802, USA
| | - Zifei Pei
- Department of Biology, Pennsylvania State University, University Park, PA 16802, USA
| | - Jizhong Zou
- Systems Biology Center, National Heart, Lung, and Blood Institute, NIH, Bethesda, Rockville, MD 20892, USA
| | - Yongsheng Shi
- Department of Microbiology & Molecular Genetics, School of Medicine, University of California, Irvine, CA 92697, USA
| | - Yingwei Mao
- Department of Biology, Pennsylvania State University, University Park, PA 16802, USA
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6
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Yang X, Triboulet R, Liu Q, Sendinc E, Gregory RI. Exon junction complex shapes the m 6A epitranscriptome. Nat Commun 2022; 13:7904. [PMID: 36550132 PMCID: PMC9780246 DOI: 10.1038/s41467-022-35643-1] [Citation(s) in RCA: 38] [Impact Index Per Article: 19.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2022] [Accepted: 12/14/2022] [Indexed: 12/24/2022] Open
Abstract
N6-methyladenosine (m6A), the most abundant modification of mRNA, is essential for normal development and dysregulation promotes cancer. m6A is highly enriched in the 3' untranslated region (UTR) of a large subset of mRNAs to influence mRNA stability and/or translation. However, the mechanism responsible for the observed m6A distribution remains enigmatic. Here we find the exon junction complex shapes the m6A landscape by blocking METTL3-mediated m6A modification close to exon junctions within coding sequence (CDS). Depletion of EIF4A3, a core component of the EJC, causes increased METTL3 binding and m6A modification of short internal exons, and sites close to exon-exon junctions within mRNA. Reporter gene experiments further support the role of splicing and EIF4A3 deposition in controlling m6A modification via the local steric blockade of METTL3. Our results explain how characteristic patterns of m6A mRNA modification are established and uncover a role of the EJC in shaping the m6A epitranscriptome.
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Affiliation(s)
- Xin Yang
- Stem Cell Program, Division of Hematology/Oncology, Boston Children's Hospital, Boston, MA, 02115, USA
- Department of Biological Chemistry and Molecular Pharmacology, Harvard Medical School, Boston, MA, 02115, USA
| | - Robinson Triboulet
- Stem Cell Program, Division of Hematology/Oncology, Boston Children's Hospital, Boston, MA, 02115, USA
- Department of Biological Chemistry and Molecular Pharmacology, Harvard Medical School, Boston, MA, 02115, USA
- Twentyeight-Seven Therapeutics, Watertown, MA, 02472, USA
| | - Qi Liu
- Stem Cell Program, Division of Hematology/Oncology, Boston Children's Hospital, Boston, MA, 02115, USA
- Department of Biological Chemistry and Molecular Pharmacology, Harvard Medical School, Boston, MA, 02115, USA
- Rice Research Institute, Guangdong Academy of Agricultural Sciences, Guangzhou, 510640, China
- Guangdong Key Laboratory of New Technology in Rice Breeding, Guangzhou, 510640, China
| | - Erdem Sendinc
- Stem Cell Program, Division of Hematology/Oncology, Boston Children's Hospital, Boston, MA, 02115, USA
- Department of Biological Chemistry and Molecular Pharmacology, Harvard Medical School, Boston, MA, 02115, USA
| | - Richard I Gregory
- Stem Cell Program, Division of Hematology/Oncology, Boston Children's Hospital, Boston, MA, 02115, USA.
- Department of Biological Chemistry and Molecular Pharmacology, Harvard Medical School, Boston, MA, 02115, USA.
- Department of Pediatrics, Harvard Medical School, Boston, MA, 02115, USA.
- Harvard Stem Cell Institute, Cambridge, MA, 02138, USA.
- Harvard Initiative for RNA Medicine, Boston, MA, 02115, USA.
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7
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Martino F, Varadarajan NM, Perestrelo AR, Hejret V, Durikova H, Vukic D, Horvath V, Cavalieri F, Caruso F, Albihlal WS, Gerber AP, O'Connell MA, Vanacova S, Pagliari S, Forte G. The mechanical regulation of RNA binding protein hnRNPC in the failing heart. Sci Transl Med 2022; 14:eabo5715. [PMID: 36417487 DOI: 10.1126/scitranslmed.abo5715] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Abstract
Cardiac pathologies are characterized by intense remodeling of the extracellular matrix (ECM) that eventually leads to heart failure. Cardiomyocytes respond to the ensuing biomechanical stress by reexpressing fetal contractile proteins via transcriptional and posttranscriptional processes, such as alternative splicing (AS). Here, we demonstrate that the heterogeneous nuclear ribonucleoprotein C (hnRNPC) is up-regulated and relocates to the sarcomeric Z-disc upon ECM pathological remodeling. We show that this is an active site of localized translation, where the ribonucleoprotein associates with the translation machinery. Alterations in hnRNPC expression, phosphorylation, and localization can be mechanically determined and affect the AS of mRNAs involved in mechanotransduction and cardiovascular diseases, including Hippo pathway effector Yes-associated protein 1. We propose that cardiac ECM remodeling serves as a switch in RNA metabolism by affecting an associated regulatory protein of the spliceosome apparatus. These findings offer new insights on the mechanism of mRNA homeostatic mechanoregulation in pathological conditions.
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Affiliation(s)
- Fabiana Martino
- International Clinical Research Center (ICRC), St. Anne's University Hospital, CZ-65691 Brno, Czech Republic.,Faculty of Medicine, Department of Biology, Masaryk University, CZ-62500 Brno, Czech Republic.,Competence Center for Mechanobiology in Regenerative Medicine, INTERREG ATCZ133, CZ-62500 Brno, Czech Republic.,Cardiac Section, National Heart and Lung Institute (NHLI), Faculty of Medicine, Imperial College London, London W12 0NN, UK
| | - Nandan Mysore Varadarajan
- Central European Institute of Technology (CEITEC), Masaryk University, CZ-62500 Brno, Czech Republic
| | - Ana Rubina Perestrelo
- International Clinical Research Center (ICRC), St. Anne's University Hospital, CZ-65691 Brno, Czech Republic
| | - Vaclav Hejret
- Central European Institute of Technology (CEITEC), Masaryk University, CZ-62500 Brno, Czech Republic.,National Centre for Biomolecular Research, Masaryk University, CZ-62500 Brno, Czech Republic
| | - Helena Durikova
- International Clinical Research Center (ICRC), St. Anne's University Hospital, CZ-65691 Brno, Czech Republic
| | - Dragana Vukic
- Central European Institute of Technology (CEITEC), Masaryk University, CZ-62500 Brno, Czech Republic
| | - Vladimir Horvath
- International Clinical Research Center (ICRC), St. Anne's University Hospital, CZ-65691 Brno, Czech Republic.,Centre for Cardiovascular and Transplant Surgery, CZ-60200 Brno, Czech Republic
| | - Francesca Cavalieri
- Department of Chemical Engineering, University of Melbourne, Parkville, Victoria 3010, Australia.,Dipartimento di Scienze e Tecnologie Chimiche, Università degli Studi di Roma Tor Vergata, 00133 Rome, Italy
| | - Frank Caruso
- Centre for Cardiovascular and Transplant Surgery, CZ-60200 Brno, Czech Republic
| | | | - André P Gerber
- Department of Microbial Sciences, Faculty of Health and Medical Sciences, University of Surrey, Guildford GU2 7XH, UK
| | - Mary A O'Connell
- Central European Institute of Technology (CEITEC), Masaryk University, CZ-62500 Brno, Czech Republic
| | - Stepanka Vanacova
- Central European Institute of Technology (CEITEC), Masaryk University, CZ-62500 Brno, Czech Republic
| | - Stefania Pagliari
- International Clinical Research Center (ICRC), St. Anne's University Hospital, CZ-65691 Brno, Czech Republic.,Competence Center for Mechanobiology in Regenerative Medicine, INTERREG ATCZ133, CZ-62500 Brno, Czech Republic
| | - Giancarlo Forte
- International Clinical Research Center (ICRC), St. Anne's University Hospital, CZ-65691 Brno, Czech Republic.,Competence Center for Mechanobiology in Regenerative Medicine, INTERREG ATCZ133, CZ-62500 Brno, Czech Republic.,School of Cardiovascular and Metabolic Medicine & Sciences, King's College London, London WC2R 2LS, UK
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8
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Subcellular spatial transcriptomics identifies three mechanistically different classes of localizing RNAs. Nat Commun 2022; 13:6355. [PMID: 36289223 PMCID: PMC9606379 DOI: 10.1038/s41467-022-34004-2] [Citation(s) in RCA: 10] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2021] [Accepted: 10/03/2022] [Indexed: 12/25/2022] Open
Abstract
Intracellular RNA localization is a widespread and dynamic phenomenon that compartmentalizes gene expression and contributes to the functional polarization of cells. Thus far, mechanisms of RNA localization identified in Drosophila have been based on a few RNAs in different tissues, and a comprehensive mechanistic analysis of RNA localization in a single tissue is lacking. Here, by subcellular spatial transcriptomics we identify RNAs localized in the apical and basal domains of the columnar follicular epithelium (FE) and we analyze the mechanisms mediating their localization. Whereas the dynein/BicD/Egl machinery controls apical RNA localization, basally-targeted RNAs require kinesin-1 to overcome a default dynein-mediated transport. Moreover, a non-canonical, translation- and dynein-dependent mechanism mediates apical localization of a subgroup of dynein-activating adaptor-encoding RNAs (BicD, Bsg25D, hook). Altogether, our study identifies at least three mechanisms underlying RNA localization in the FE, and suggests a possible link between RNA localization and dynein/dynactin/adaptor complex formation in vivo.
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9
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Martin H, Rupkey J, Asthana S, Yoon J, Patel S, Mott J, Pei Z, Mao Y. Diverse Roles of the Exon Junction Complex Factors in the Cell Cycle, Cancer, and Neurodevelopmental Disorders-Potential for Therapeutic Targeting. Int J Mol Sci 2022; 23:ijms231810375. [PMID: 36142288 PMCID: PMC9499366 DOI: 10.3390/ijms231810375] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2022] [Revised: 09/01/2022] [Accepted: 09/05/2022] [Indexed: 12/04/2022] Open
Abstract
The exon junction complex (EJC) plays a crucial role in regulating gene expression at the levels of alternative splicing, translation, mRNA localization, and nonsense-mediated decay (NMD). The EJC is comprised of three core proteins: RNA-binding motif 8A (RBM8A), Mago homolog (MAGOH), eukaryotic initiation factor 4A3 (eIF4A3), and a peripheral EJC factor, metastatic lymph node 51 (MLN51), in addition to other peripheral factors whose structural integration is activity-dependent. The physiological and mechanistic roles of the EJC in contribution to molecular, cellular, and organismal level function continue to be explored for potential insights into genetic or pathological dysfunction. The EJC’s specific role in the cell cycle and its implications in cancer and neurodevelopmental disorders prompt enhanced investigation of the EJC as a potential target for these diseases. In this review, we highlight the current understanding of the EJC’s position in the cell cycle, its relation to cancer and developmental diseases, and potential avenues for therapeutic targeting.
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Affiliation(s)
- Hannah Martin
- Department of Biology, Pennsylvania State University, University Park, State College, PA 16802, USA
| | - Julian Rupkey
- Department of Biology, Pennsylvania State University, University Park, State College, PA 16802, USA
| | - Shravan Asthana
- Department of Biology, Pennsylvania State University, University Park, State College, PA 16802, USA
- Feinberg School of Medicine, Northwestern University, 303 East Superior Street, Chicago, IL 60611, USA
| | - Joy Yoon
- Department of Biology, Pennsylvania State University, University Park, State College, PA 16802, USA
| | - Shray Patel
- Department of Biology, Pennsylvania State University, University Park, State College, PA 16802, USA
| | - Jennifer Mott
- Department of Biology, Pennsylvania State University, University Park, State College, PA 16802, USA
| | - Zifei Pei
- Department of Biology, Pennsylvania State University, University Park, State College, PA 16802, USA
| | - Yingwei Mao
- Department of Biology, Pennsylvania State University, University Park, State College, PA 16802, USA
- Correspondence:
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10
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Müntjes K, Devan SK, Reichert AS, Feldbrügge M. Linking transport and translation of mRNAs with endosomes and mitochondria. EMBO Rep 2021; 22:e52445. [PMID: 34402186 PMCID: PMC8490996 DOI: 10.15252/embr.202152445] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/12/2021] [Revised: 07/06/2021] [Accepted: 07/27/2021] [Indexed: 01/01/2023] Open
Abstract
In eukaryotic cells, proteins are targeted to their final subcellular locations with precise timing. A key underlying mechanism is the active transport of cognate mRNAs, which in many systems can be linked intimately to membrane trafficking. A prominent example is the long-distance endosomal transport of mRNAs and their local translation. Here, we describe current highlights of fundamental mechanisms of the underlying transport process as well as of biological functions ranging from endosperm development in plants to fungal pathogenicity and neuronal processes. Translation of endosome-associated mRNAs often occurs at the cytoplasmic surface of endosomes, a process that is needed for membrane-assisted formation of heteromeric protein complexes and for accurate subcellular targeting of proteins. Importantly, endosome-coupled translation of mRNAs encoding mitochondrial proteins, for example, seems to be particularly important for efficient organelle import and for regulating subcellular mitochondrial activity. In essence, these findings reveal a new mechanism of loading newly synthesised proteins onto endocytic membranes enabling intimate crosstalk between organelles. The novel link between endosomes and mitochondria adds an inspiring new level of complexity to trafficking and organelle biology.
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Affiliation(s)
- Kira Müntjes
- Institute of MicrobiologyCluster of Excellence on Plant SciencesHeinrich Heine University DüsseldorfDüsseldorfGermany
| | - Senthil Kumar Devan
- Institute of MicrobiologyCluster of Excellence on Plant SciencesHeinrich Heine University DüsseldorfDüsseldorfGermany
| | - Andreas S Reichert
- Institute of Biochemistry and Molecular Biology IMedical Faculty and University Hospital DüsseldorfHeinrich Heine University DüsseldorfDüsseldorfGermany
| | - Michael Feldbrügge
- Institute of MicrobiologyCluster of Excellence on Plant SciencesHeinrich Heine University DüsseldorfDüsseldorfGermany
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11
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RIPiT-Seq: A tandem immunoprecipitation approach to reveal global binding landscape of multisubunit ribonucleoproteins. Methods Enzymol 2021; 655:401-425. [PMID: 34183131 DOI: 10.1016/bs.mie.2021.03.019] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Abstract
RNA-binding proteins (RBPs) regulate all aspects of RNA metabolism. The ability to identify RNA targets bound by RBPs is critical for understanding RBP function. While powerful techniques are available to identify binding sites of individual RBPs at high resolution, it remains challenging to unravel binding sites of multicomponent ribonucleoproteins (RNPs) where multiple RBPs or proteins function cooperatively to bind to target RNAs. To fill this gap, we have previously developed RNA Immunoprecipitation in Tandem followed by high-throughput sequencing (RIPiT-seq) to characterize RNA targets of compositionally distinct RNP complexes by sequentially immunoprecipitating two proteins from the same RNP and sequencing the co-purifying RNA footprints. Here, we provide an updated and improved protocol for RIPiT-seq. In this protocol, we have used CRISPR-Cas9 to introduce affinity tag to endogenous protein of interest to capture a more representative state of an RNP complex. We present a modified protocol for library preparation for high-throughput sequencing so that it exclusively uses equipment and reagents available in a standard molecular biology lab. This updated custom library preparation protocol is compatible with commercial PCR multiplexing systems for Illumina sequencing platform for simultaneous and cost-effective analysis of large number of samples.
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Joseph B, Lai EC. The Exon Junction Complex and intron removal prevent re-splicing of mRNA. PLoS Genet 2021; 17:e1009563. [PMID: 34033644 PMCID: PMC8184009 DOI: 10.1371/journal.pgen.1009563] [Citation(s) in RCA: 16] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2020] [Revised: 06/07/2021] [Accepted: 04/26/2021] [Indexed: 01/23/2023] Open
Abstract
Accurate splice site selection is critical for fruitful gene expression. Recently, the mammalian EJC was shown to repress competing, cryptic, splice sites (SS). However, the evolutionary generality of this remains unclear. Here, we demonstrate the Drosophila EJC suppresses hundreds of functional cryptic SS, even though most bear weak splicing motifs and are seemingly incompetent. Mechanistically, the EJC directly conceals cryptic splicing elements by virtue of its position-specific recruitment, preventing aberrant SS definition. Unexpectedly, we discover the EJC inhibits scores of regenerated 5' and 3' recursive SS on segments that have already undergone splicing, and that loss of EJC regulation triggers faulty resplicing of mRNA. An important corollary is that certain intronless cDNA constructs yield unanticipated, truncated transcripts generated by resplicing. We conclude the EJC has conserved roles to defend transcriptome fidelity by (1) repressing illegitimate splice sites on pre-mRNAs, and (2) preventing inadvertent activation of such sites on spliced segments.
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Affiliation(s)
- Brian Joseph
- Developmental Biology Program, Sloan Kettering Institute, New York, New York, United States of America
- Louis V. Gerstner, Jr. Graduate School of Biomedical Sciences, Memorial Sloan Kettering Cancer Center, New York, New York, United States of America
| | - Eric C. Lai
- Developmental Biology Program, Sloan Kettering Institute, New York, New York, United States of America
- Louis V. Gerstner, Jr. Graduate School of Biomedical Sciences, Memorial Sloan Kettering Cancer Center, New York, New York, United States of America
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Patton RD, Sanjeev M, Woodward LA, Mabin JW, Bundschuh R, Singh G. Chemical crosslinking enhances RNA immunoprecipitation for efficient identification of binding sites of proteins that photo-crosslink poorly with RNA. RNA (NEW YORK, N.Y.) 2020; 26:1216-1233. [PMID: 32467309 PMCID: PMC7430673 DOI: 10.1261/rna.074856.120] [Citation(s) in RCA: 19] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/13/2020] [Accepted: 05/17/2020] [Indexed: 05/14/2023]
Abstract
In eukaryotic cells, proteins that associate with RNA regulate its activity to control cellular function. To fully illuminate the basis of RNA function, it is essential to identify such RNA-associated proteins, their mode of action on RNA, and their preferred RNA targets and binding sites. By analyzing catalogs of human RNA-associated proteins defined by ultraviolet light (UV)-dependent and -independent approaches, we classify these proteins into two major groups: (i) the widely recognized RNA binding proteins (RBPs), which bind RNA directly and UV-crosslink efficiently to RNA, and (ii) a new group of RBP-associated factors (RAFs), which bind RNA indirectly via RBPs and UV-crosslink poorly to RNA. As the UV crosslinking and immunoprecipitation followed by sequencing (CLIP-seq) approach will be unsuitable to identify binding sites of RAFs, we show that formaldehyde crosslinking stabilizes RAFs within ribonucleoproteins to allow for their immunoprecipitation under stringent conditions. Using an RBP (CASC3) and an RAF (RNPS1) within the exon junction complex (EJC) as examples, we show that formaldehyde crosslinking combined with RNA immunoprecipitation in tandem followed by sequencing (xRIPiT-seq) far exceeds CLIP-seq to identify binding sites of RNPS1. xRIPiT-seq reveals that RNPS1 occupancy is increased on exons immediately upstream of strong recursively spliced exons, which depend on the EJC for their inclusion.
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Affiliation(s)
- Robert D Patton
- Department of Physics, The Ohio State University, Columbus, Ohio 43210, USA
- Center for RNA Biology, The Ohio State University, Columbus, Ohio 43210, USA
| | - Manu Sanjeev
- Center for RNA Biology, The Ohio State University, Columbus, Ohio 43210, USA
- Department of Molecular Genetics, The Ohio State University, Columbus, Ohio 43210, USA
| | - Lauren A Woodward
- Center for RNA Biology, The Ohio State University, Columbus, Ohio 43210, USA
- Department of Molecular Genetics, The Ohio State University, Columbus, Ohio 43210, USA
| | - Justin W Mabin
- Center for RNA Biology, The Ohio State University, Columbus, Ohio 43210, USA
- Department of Molecular Genetics, The Ohio State University, Columbus, Ohio 43210, USA
| | - Ralf Bundschuh
- Department of Physics, The Ohio State University, Columbus, Ohio 43210, USA
- Center for RNA Biology, The Ohio State University, Columbus, Ohio 43210, USA
- Department of Chemistry and Biochemistry, The Ohio State University, Columbus, Ohio 43210, USA
- Division of Hematology, Department of Internal Medicine, The Ohio State University, Columbus, Ohio 43210, USA
| | - Guramrit Singh
- Center for RNA Biology, The Ohio State University, Columbus, Ohio 43210, USA
- Department of Molecular Genetics, The Ohio State University, Columbus, Ohio 43210, USA
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A Day in the Life of the Exon Junction Complex. Biomolecules 2020; 10:biom10060866. [PMID: 32517083 PMCID: PMC7355637 DOI: 10.3390/biom10060866] [Citation(s) in RCA: 49] [Impact Index Per Article: 12.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/01/2020] [Revised: 05/29/2020] [Accepted: 06/02/2020] [Indexed: 12/12/2022] Open
Abstract
The exon junction complex (EJC) is an abundant messenger ribonucleoprotein (mRNP) component that is assembled during splicing and binds to mRNAs upstream of exon-exon junctions. EJCs accompany the mRNA during its entire life in the nucleus and the cytoplasm and communicate the information about the splicing process and the position of introns. Specifically, the EJC’s core components and its associated proteins regulate different steps of gene expression, including pre-mRNA splicing, mRNA export, translation, and nonsense-mediated mRNA decay (NMD). This review summarizes the most important functions and main protagonists in the life of the EJC. It also provides an overview of the latest findings on the assembly, composition and molecular activities of the EJC and presents them in the chronological order, in which they play a role in the EJC’s life cycle.
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Gangras P, Gallagher TL, Parthun MA, Yi Z, Patton RD, Tietz KT, Deans NC, Bundschuh R, Amacher SL, Singh G. Zebrafish rbm8a and magoh mutants reveal EJC developmental functions and new 3'UTR intron-containing NMD targets. PLoS Genet 2020; 16:e1008830. [PMID: 32502192 PMCID: PMC7310861 DOI: 10.1371/journal.pgen.1008830] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2019] [Revised: 06/23/2020] [Accepted: 05/05/2020] [Indexed: 12/11/2022] Open
Abstract
Many post-transcriptional mechanisms operate via mRNA 3'UTRs to regulate protein expression, and such controls are crucial for development. We show that homozygous mutations in two zebrafish exon junction complex (EJC) core genes rbm8a and magoh leads to muscle disorganization, neural cell death, and motor neuron outgrowth defects, as well as dysregulation of mRNAs subjected to nonsense-mediated mRNA decay (NMD) due to translation termination ≥ 50 nts upstream of the last exon-exon junction. Intriguingly, we find that EJC-dependent NMD also regulates a subset of transcripts that contain 3'UTR introns (3'UI) < 50 nts downstream of a stop codon. Some transcripts containing such stop codon-proximal 3'UI are also NMD-sensitive in cultured human cells and mouse embryonic stem cells. We identify 167 genes that contain a conserved proximal 3'UI in zebrafish, mouse and humans. foxo3b is one such proximal 3'UI-containing gene that is upregulated in zebrafish EJC mutant embryos, at both mRNA and protein levels, and loss of foxo3b function in EJC mutant embryos significantly rescues motor axon growth defects. These data are consistent with EJC-dependent NMD regulating foxo3b mRNA to control protein expression during zebrafish development. Our work shows that the EJC is critical for normal zebrafish development and suggests that proximal 3'UIs may serve gene regulatory function in vertebrates.
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Affiliation(s)
- Pooja Gangras
- Department of Molecular Genetics, The Ohio State University, Ohio, United States of America
- Center for RNA Biology, The Ohio State University, Ohio, United States of America
| | - Thomas L. Gallagher
- Department of Molecular Genetics, The Ohio State University, Ohio, United States of America
- Center for RNA Biology, The Ohio State University, Ohio, United States of America
| | - Michael A. Parthun
- Department of Molecular Genetics, The Ohio State University, Ohio, United States of America
- Center for RNA Biology, The Ohio State University, Ohio, United States of America
| | - Zhongxia Yi
- Department of Molecular Genetics, The Ohio State University, Ohio, United States of America
- Center for RNA Biology, The Ohio State University, Ohio, United States of America
| | - Robert D. Patton
- Center for RNA Biology, The Ohio State University, Ohio, United States of America
- Department of Physics, The Ohio State University, Ohio, United States of America
| | - Kiel T. Tietz
- Department of Molecular Genetics, The Ohio State University, Ohio, United States of America
- Center for RNA Biology, The Ohio State University, Ohio, United States of America
| | - Natalie C. Deans
- Department of Molecular Genetics, The Ohio State University, Ohio, United States of America
- Center for RNA Biology, The Ohio State University, Ohio, United States of America
| | - Ralf Bundschuh
- Center for RNA Biology, The Ohio State University, Ohio, United States of America
- Department of Physics, The Ohio State University, Ohio, United States of America
- Department of Chemistry and Biochemistry, The Ohio State University, Ohio, United States of America
- Division of Hematology, Department of Internal Medicine, The Ohio State University, Ohio, United States of America
| | - Sharon L. Amacher
- Department of Molecular Genetics, The Ohio State University, Ohio, United States of America
- Center for RNA Biology, The Ohio State University, Ohio, United States of America
- Department of Biological Chemistry and Pharmacology, The Ohio State University, Ohio, United States of America
- Center for Muscle Health and Neuromuscular Disorders, The Ohio State University and Nationwide Children’s Hospital, Ohio, United States of America
| | - Guramrit Singh
- Department of Molecular Genetics, The Ohio State University, Ohio, United States of America
- Center for RNA Biology, The Ohio State University, Ohio, United States of America
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