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Chen R, Stainier W, Dufourt J, Lagha M, Lehmann R. Direct observation of translational activation by a ribonucleoprotein granule. Nat Cell Biol 2024; 26:1322-1335. [PMID: 38965420 PMCID: PMC11321996 DOI: 10.1038/s41556-024-01452-5] [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: 09/13/2023] [Accepted: 05/30/2024] [Indexed: 07/06/2024]
Abstract
Biomolecular condensates organize biochemical processes at the subcellular level and can provide spatiotemporal regulation within a cell. Among these, ribonucleoprotein (RNP) granules are storage hubs for translationally repressed mRNA. Whether RNP granules can also activate translation and how this could be achieved remains unclear. Here, using single-molecule imaging, we demonstrate that the germ cell-determining RNP granules in Drosophila embryos are sites for active translation of nanos mRNA. Nanos translation occurs preferentially at the germ granule surface with the 3' UTR buried within the granule. Smaug, a cytosolic RNA-binding protein, represses nanos translation, which is relieved when Smaug is sequestered to the germ granule by the scaffold protein Oskar. Together, our findings uncover a molecular process by which RNP granules achieve localized protein synthesis through the compartmentalized loss of translational repression.
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Affiliation(s)
- Ruoyu Chen
- Whitehead Institute for Biomedical Research, Cambridge, MA, USA
- Vilcek Institute of Graduate Studies, NYU School of Medicine, New York, NY, USA
| | - William Stainier
- Whitehead Institute for Biomedical Research, Cambridge, MA, USA
- Immunobiology Laboratory, The Francis Crick Institute, London, UK
| | - Jeremy Dufourt
- Institut de Génétique Moléculaire de Montpellier, University of Montpellier, Montpellier, France
- Institut de Recherche en Infectiologie de Montpellier, University of Montpellier, Montpellier, France
| | - Mounia Lagha
- Institut de Génétique Moléculaire de Montpellier, University of Montpellier, Montpellier, France
| | - Ruth Lehmann
- Whitehead Institute for Biomedical Research, Cambridge, MA, USA.
- Department of Biology, Massachusetts Institute of Technology, Cambridge, MA, USA.
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2
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Gao M. Me31B: a key repressor in germline regulation and beyond. Biosci Rep 2024; 44:BSR20231769. [PMID: 38606619 PMCID: PMC11065648 DOI: 10.1042/bsr20231769] [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: 02/05/2024] [Revised: 04/10/2024] [Accepted: 04/11/2024] [Indexed: 04/13/2024] Open
Abstract
Maternally Expressed at 31B (Me31B), an evolutionarily conserved ATP-dependent RNA helicase, plays an important role in the development of the germline across diverse animal species. Its cellular functionality has been posited as a translational repressor, participating in various RNA metabolism pathways to intricately regulate the spatiotemporal expression of RNAs. Despite its evident significance, the precise role and mechanistic underpinnings of Me31B remain insufficiently understood. This article endeavors to comprehensively review historic and recent research on Me31B, distill the major findings, discern generalizable patterns in Me31B's functions across different research contexts, and provide insights into its fundamental role and mechanism of action. The primary focus of this article centers on elucidating the role of Drosophila Me31B within the germline, while concurrently delving into pertinent research on its orthologs within other species and cellular systems.
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Affiliation(s)
- Ming Gao
- Biology Department, Indiana University Northwest, Gary, IN, U.S.A
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3
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Xiao W, Halabi R, Lin CH, Nazim M, Yeom KH, Black DL. The lncRNA Malat1 is trafficked to the cytoplasm as a localized mRNA encoding a small peptide in neurons. Genes Dev 2024; 38:294-307. [PMID: 38688681 PMCID: PMC11146593 DOI: 10.1101/gad.351557.124] [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: 01/23/2024] [Accepted: 04/12/2024] [Indexed: 05/02/2024]
Abstract
Synaptic function in neurons is modulated by local translation of mRNAs that are transported to distal portions of axons and dendrites. The metastasis-associated lung adenocarcinoma transcript 1 (MALAT1) is broadly expressed across cell types, almost exclusively as a nuclear long noncoding RNA. We found that in differentiating neurons, a portion of Malat1 RNA redistributes to the cytoplasm. Depletion of Malat1 using antisense oligonucleotides (ASOs) stimulates the expression of particular pre- and postsynaptic proteins, implicating Malat1 in their regulation. Neuronal Malat1 is localized in puncta of both axons and dendrites that costain with Staufen1 protein, similar to neuronal RNA granules formed by locally translated mRNAs. Ribosome profiling of cultured mouse cortical neurons identified ribosome footprints within a 5' region of Malat1 containing short open reading frames. The upstream-most reading frame (M1) of the Malat1 locus was linked to the GFP-coding sequence in mouse embryonic stem cells. When these gene-edited cells were differentiated into glutamatergic neurons, the M1-GFP fusion protein was expressed. Antibody staining for the M1 peptide confirmed its presence in wild-type neurons and showed that M1 expression was enhanced by synaptic stimulation with KCl. Our results indicate that Malat1 serves as a cytoplasmic coding RNA in the brain that is both modulated by and modulates synaptic function.
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Affiliation(s)
- Wen Xiao
- Department of Microbiology, Immunology, and Molecular Genetics, David Geffen School of Medicine, University of California Los Angeles, Los Angeles, California 90095, USA
| | - Reem Halabi
- Department of Microbiology, Immunology, and Molecular Genetics, David Geffen School of Medicine, University of California Los Angeles, Los Angeles, California 90095, USA
| | - Chia-Ho Lin
- Department of Microbiology, Immunology, and Molecular Genetics, David Geffen School of Medicine, University of California Los Angeles, Los Angeles, California 90095, USA
| | - Mohammad Nazim
- Department of Microbiology, Immunology, and Molecular Genetics, David Geffen School of Medicine, University of California Los Angeles, Los Angeles, California 90095, USA
| | - Kyu-Hyeon Yeom
- Department of Microbiology, Immunology, and Molecular Genetics, David Geffen School of Medicine, University of California Los Angeles, Los Angeles, California 90095, USA
| | - Douglas L Black
- Department of Microbiology, Immunology, and Molecular Genetics, David Geffen School of Medicine, University of California Los Angeles, Los Angeles, California 90095, USA;
- Molecular Biology Institute, University of California Los Angeles, Los Angeles, California 90095, USA
- Eli and Edythe Broad Center of Regenerative Medicine and Stem Cell Research, University of California Los Angeles, Los Angeles, California 90095, USA
- Jonsson Comprehensive Cancer Center, David Geffen School of Medicine, University of California Los Angeles, Los Angeles, California 90095, USA
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Xiao W, Halabi R, Lin CH, Nazim M, Yeom KH, Black DL. The lncRNA Malat1 is trafficked to the cytoplasm as a localized mRNA encoding a small peptide in neurons. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.02.01.578240. [PMID: 38352368 PMCID: PMC10862813 DOI: 10.1101/2024.02.01.578240] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 02/25/2024]
Abstract
Synaptic function is modulated by local translation of mRNAs that are transported to distal portions of axons and dendrites. The Metastasis-associated lung adenocarcinoma transcript 1 (MALAT1) is broadly expressed across cell types, almost exclusively as a nuclear non-coding RNA. We found that in differentiating neurons, a portion of Malat1 RNA redistributes to the cytoplasm. Depletion of Malat1 from neurons stimulated expression of particular pre- and post- synaptic proteins, implicating Malat1 in their regulation. Neuronal Malat1 is localized to both axons and dendrites in puncta that co-stain with Staufen1 protein, similar to neuronal granules formed by locally translated mRNAs. Ribosome profiling of mouse cortical neurons identified ribosome footprints within a region of Malat1 containing short open reading frames. The upstream-most reading frame (M1) of the Malat1 locus was linked to the GFP coding sequence in mouse ES cells. When these gene-edited cells were differentiated into glutamatergic neurons, the M1-GFP fusion protein was expressed. Antibody staining for the M1 peptide confirmed its presence in wildtype neurons, and showed enhancement of M1 expression after synaptic stimulation with KCL. Our results indicate that Malat1 serves as a cytoplasmic coding RNA in the brain that is both modulated by and modulates synaptic function.
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Affiliation(s)
- Wen Xiao
- Department of Microbiology, Immunology, and Molecular Genetics, David Geffen School of Medicine, University of California, Los Angeles, CA 90095
| | - Reem Halabi
- Department of Microbiology, Immunology, and Molecular Genetics, David Geffen School of Medicine, University of California, Los Angeles, CA 90095
| | - Chia-Ho Lin
- Department of Microbiology, Immunology, and Molecular Genetics, David Geffen School of Medicine, University of California, Los Angeles, CA 90095
| | - Mohammad Nazim
- Department of Microbiology, Immunology, and Molecular Genetics, David Geffen School of Medicine, University of California, Los Angeles, CA 90095
| | - Kyu-Hyeon Yeom
- Department of Microbiology, Immunology, and Molecular Genetics, David Geffen School of Medicine, University of California, Los Angeles, CA 90095
| | - Douglas L Black
- Department of Microbiology, Immunology, and Molecular Genetics, David Geffen School of Medicine, University of California, Los Angeles, CA 90095
- Molecular Biology Institute, David Geffen School of Medicine, University of California, Los Angeles, CA 90095
- Eli and Edythe Broad Center of Regenerative Medicine and Stem Cell Research, David Geffen School of Medicine, University of California, Los Angeles, CA 90095
- Jonsson Comprehensive Cancer Center, David Geffen School of Medicine, University of California, Los Angeles, CA 90095
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5
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Wilby EL, Weil TT. Relating the Biogenesis and Function of P Bodies in Drosophila to Human Disease. Genes (Basel) 2023; 14:1675. [PMID: 37761815 PMCID: PMC10530015 DOI: 10.3390/genes14091675] [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: 07/31/2023] [Revised: 08/17/2023] [Accepted: 08/18/2023] [Indexed: 09/29/2023] Open
Abstract
Drosophila has been a premier model organism for over a century and many discoveries in flies have furthered our understanding of human disease. Flies have been successfully applied to many aspects of health-based research spanning from behavioural addiction, to dysplasia, to RNA dysregulation and protein misfolding. Recently, Drosophila tissues have been used to study biomolecular condensates and their role in multicellular systems. Identified in a wide range of plant and animal species, biomolecular condensates are dynamic, non-membrane-bound sub-compartments that have been observed and characterised in the cytoplasm and nuclei of many cell types. Condensate biology has exciting research prospects because of their diverse roles within cells, links to disease, and potential for therapeutics. In this review, we will discuss processing bodies (P bodies), a conserved biomolecular condensate, with a particular interest in how Drosophila can be applied to advance our understanding of condensate biogenesis and their role in disease.
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Affiliation(s)
| | - Timothy T. Weil
- Department of Zoology, University of Cambridge, Downing Street, Cambridge CB2 3EJ, UK;
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Emerging Roles of RNA-Binding Proteins in Neurodevelopment. J Dev Biol 2022; 10:jdb10020023. [PMID: 35735914 PMCID: PMC9224834 DOI: 10.3390/jdb10020023] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/20/2022] [Revised: 06/02/2022] [Accepted: 06/08/2022] [Indexed: 02/06/2023] Open
Abstract
Diverse cell types in the central nervous system (CNS) are generated by a relatively small pool of neural stem cells during early development. Spatial and temporal regulation of stem cell behavior relies on precise coordination of gene expression. Well-studied mechanisms include hormone signaling, transcription factor activity, and chromatin remodeling processes. Much less is known about downstream RNA-dependent mechanisms including posttranscriptional regulation, nuclear export, alternative splicing, and transcript stability. These important functions are carried out by RNA-binding proteins (RBPs). Recent work has begun to explore how RBPs contribute to stem cell function and homeostasis, including their role in metabolism, transport, epigenetic regulation, and turnover of target transcripts. Additional layers of complexity are provided by the different target recognition mechanisms of each RBP as well as the posttranslational modifications of the RBPs themselves that alter function. Altogether, these functions allow RBPs to influence various aspects of RNA metabolism to regulate numerous cellular processes. Here we compile advances in RNA biology that have added to our still limited understanding of the role of RBPs in neurodevelopment.
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Pushpalatha KV, Solyga M, Nakamura A, Besse F. RNP components condense into repressive RNP granules in the aging brain. Nat Commun 2022; 13:2782. [PMID: 35589695 PMCID: PMC9120078 DOI: 10.1038/s41467-022-30066-4] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/14/2021] [Accepted: 04/11/2022] [Indexed: 12/21/2022] Open
Abstract
Cytoplasmic RNP condensates enriched in mRNAs and proteins are found in various cell types and associated with both buffering and regulatory functions. While a clear link has been established between accumulation of aberrant RNP aggregates and progression of aging-related neurodegenerative diseases, the impact of physiological aging on neuronal RNP condensates has never been explored. Through high-resolution imaging, we uncover that RNP components progressively cluster into large yet dynamic granules in the aging Drosophila brain. We further show that age-dependent clustering is caused by an increase in the stoichiometry of the conserved helicase Me31B/DDX6, and requires PKA kinase activity. Finally, our functional analysis reveals that mRNA species recruited to RNP condensates upon aging exhibit age-dependent translational repression, indicating that co-clustering of selected mRNAs and translation regulators into repressive condensates may contribute to the specific post-transcriptional changes in gene expression observed in the course of aging. Aberrant RNA condensates are a hallmark of age-related neurodegenerative diseases. Here, the authors show that RNA condensation increases in aging Drosophila brains, triggering translation repression.
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Affiliation(s)
| | - Mathilde Solyga
- Université Côte d'Azur, CNRS, Inserm, Institut de Biologie Valrose, Nice, France
| | - Akira Nakamura
- Department of Germline Development, Institute of Molecular Embryology and Genetics, Kumamoto University, Kumamoto, Japan.,Graduate School of Pharmaceutical Sciences, Kumamoto University, Kumamoto, Japan
| | - Florence Besse
- Université Côte d'Azur, CNRS, Inserm, Institut de Biologie Valrose, Nice, France.
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Koppers M, Holt CE. Receptor-Ribosome Coupling: A Link Between Extrinsic Signals and mRNA Translation in Neuronal Compartments. Annu Rev Neurosci 2022; 45:41-61. [DOI: 10.1146/annurev-neuro-083021-110015] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Axons receive extracellular signals that help to guide growth and synapse formation during development and to maintain neuronal function and survival during maturity. These signals relay information via cell surface receptors that can initiate local intracellular signaling at the site of binding, including local messenger RNA (mRNA) translation. Direct coupling of translational machinery to receptors provides an attractive way to activate this local mRNA translation and change the local proteome with high spatiotemporal resolution. Here, we first discuss the increasing evidence that different external stimuli trigger translation of specific subsets of mRNAs in axons via receptors and thus play a prominent role in various processes in both developing and mature neurons. We then discuss the receptor-mediated molecular mechanisms that regulate local mRNA translational with a focus on direct receptor-ribosome coupling. We advance the idea that receptor-ribosome coupling provides several advantages over other translational regulation mechanisms and is a common mechanism in cell communication. Expected final online publication date for the Annual Review of Neuroscience, Volume 45 is July 2022. Please see http://www.annualreviews.org/page/journal/pubdates for revised estimates.
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Affiliation(s)
- Max Koppers
- Department of Biology, Division of Cell Biology, Neurobiology and Biophysics, Utrecht University, Utrecht, The Netherlands
| | - Christine E. Holt
- Department of Physiology, Development and Neuroscience, University of Cambridge, Cambridge, United Kingdom
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9
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Single-molecule mRNA and translation imaging in neurons. Biochem Soc Trans 2021; 49:2221-2227. [PMID: 34495323 DOI: 10.1042/bst20210313] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2021] [Revised: 08/20/2021] [Accepted: 08/23/2021] [Indexed: 11/17/2022]
Abstract
Memory-relevant neuronal plasticity is believed to require local translation of new proteins at synapses. Understanding this process has necessitated the development of tools to visualize mRNA within relevant neuronal compartments. In this review, we summarize the technical developments that now enable mRNA transcripts and their translation to be visualized at single-molecule resolution in both fixed and live cells. These tools include single-molecule fluorescence in situ hybridization (smFISH) to visualize mRNA in fixed cells, MS2/PP7 labelling for live mRNA imaging and SunTag labelling to observe the emergence of nascent polypeptides from a single translating mRNA. The application of these tools in cultured neurons and more recently in whole brains promises to revolutionize our understanding of local translation in the neuronal plasticity that underlies behavioural change.
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Vinter DJ, Hoppe C, Ashe HL. Live and fixed imaging of translation sites at single mRNA resolution in the Drosophila embryo. STAR Protoc 2021; 2:100812. [PMID: 34585149 PMCID: PMC8450298 DOI: 10.1016/j.xpro.2021.100812] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022] Open
Abstract
Significant regulation of gene expression is mediated at the translation level. Here, we describe protocols for imaging and analysis of translation at single mRNA resolution in both fixed and living Drosophila embryos. These protocols use the SunTag system, in which the protein of interest is visualized by inserting a peptide array that is recognized by a single chain antibody. Simultaneous detection of individual mRNAs using the MS2/MCP system or by smFISH allows translation sites to be identified and quantified. For complete information on the generation and use of this protocol, please refer to Vinter et al. (2021).
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Affiliation(s)
- Daisy J. Vinter
- Faculty of Biology, Medicine and Health, University of Manchester, Manchester M13 9PT, UK
| | - Caroline Hoppe
- Faculty of Biology, Medicine and Health, University of Manchester, Manchester M13 9PT, UK
| | - Hilary L. Ashe
- Faculty of Biology, Medicine and Health, University of Manchester, Manchester M13 9PT, UK
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