1
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Rangone H, Bond L, Weil TT, Glover DM. Greatwall-Endos-PP2A/B55 Twins network regulates translation and stability of maternal transcripts in the Drosophila oocyte-to-embryo transition. Open Biol 2024; 14:240065. [PMID: 38896085 DOI: 10.1098/rsob.240065] [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: 03/14/2024] [Accepted: 04/24/2024] [Indexed: 06/21/2024] Open
Abstract
The transition from oocyte to embryo requires translation of maternally provided transcripts that in Drosophila is activated by Pan Gu kinase to release a rapid succession of 13 mitotic cycles. Mitotic entry is promoted by several protein kinases that include Greatwall/Mastl, whose Endosulfine substrates antagonize Protein Phosphatase 2A (PP2A), facilitating mitotic Cyclin-dependent kinase 1/Cyclin B kinase activity. Here we show that hyperactive greatwallScant can not only be suppressed by mutants in its Endos substrate but also by mutants in Pan Gu kinase subunits. Conversely, mutants in me31B or trailer hitch, which encode a complex that represses hundreds of maternal mRNAs, enhance greatwallScant . Me31B and Trailer Hitch proteins, known substrates of Pan Gu kinase, copurify with Endos. This echoes findings that budding yeast Dhh1, orthologue of Me31B, associates with Igo1/2, orthologues of Endos and substrates of the Rim15, orthologue of Greatwall. endos-derived mutant embryos show reduced Me31B and elevated transcripts for the mitotic activators Cyclin B, Polo and Twine/Cdc25. Together, our findings demonstrate a previously unappreciated conservation of the Greatwall-Endosulfine pathway in regulating translational repressors and its interactions with the Pan Gu kinase pathway to regulate translation and/or stability of maternal mRNAs upon egg activation.
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Affiliation(s)
- Hélène Rangone
- Department of Genetics, University of Cambridge, Downing Street , Cambridge, UK
| | - Laura Bond
- Department of Genetics, University of Cambridge, Downing Street , Cambridge, UK
| | - Timothy T Weil
- Department of Zoology, University of Cambridge, Downing Street , Cambridge, UK
| | - David M Glover
- Department of Genetics, University of Cambridge, Downing Street , Cambridge, UK
- Division of Biology and Biological Engineering, California Institute of Technology, 1200 E. California Blvd , Pasadena, CA 91125, USA
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2
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Bermudez Y, Hatfield D, Muller M. A Balancing Act: The Viral-Host Battle over RNA Binding Proteins. Viruses 2024; 16:474. [PMID: 38543839 PMCID: PMC10974049 DOI: 10.3390/v16030474] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2023] [Revised: 03/16/2024] [Accepted: 03/18/2024] [Indexed: 04/01/2024] Open
Abstract
A defining feature of a productive viral infection is the co-opting of host cell resources for viral replication. Despite the host repertoire of molecular functions and biological counter measures, viruses still subvert host defenses to take control of cellular factors such as RNA binding proteins (RBPs). RBPs are involved in virtually all steps of mRNA life, forming ribonucleoprotein complexes (mRNPs) in a highly ordered and regulated process to control RNA fate and stability in the cell. As such, the hallmark of the viral takeover of a cell is the reshaping of RNA fate to modulate host gene expression and evade immune responses by altering RBP interactions. Here, we provide an extensive review of work in this area, particularly on the duality of the formation of RNP complexes that can be either pro- or antiviral. Overall, in this review, we highlight the various ways viruses co-opt RBPs to regulate RNA stability and modulate the outcome of infection by gathering novel insights gained from research studies in this field.
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Affiliation(s)
| | | | - Mandy Muller
- Department of Microbiology, University of Massachusetts, Amherst, MA 01003, USA; (Y.B.); (D.H.)
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3
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Williams TD, Winaya A, Joshua I, Rousseau A. Proteasome assembly chaperone translation upon stress requires Ede1 phase separation at the plasma membrane. iScience 2024; 27:108732. [PMID: 38235332 PMCID: PMC10792233 DOI: 10.1016/j.isci.2023.108732] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2023] [Revised: 10/21/2023] [Accepted: 12/11/2023] [Indexed: 01/19/2024] Open
Abstract
Proteome adaptation is key to cells surviving stresses. Increased translation of proteasome assembly chaperones (PACs) is critical for increasing proteasome assembly and cell degradative capacity. The endocytic protein Ede1 recruits PAC mRNA to cortical actin patches in Saccharomyces cerevisiae for translation upon stress. We show, through genetic and pharmacological studies, that this is mediated by the capacity of Ede1 to phase separate. PAC expression is maintained when we exchange the phase separating domains from Ede1 for those of unrelated proteins. Without these phase separating regions, PAC expression is not induced upon stress, preventing increased proteasome assembly, causing cell death. This work identifies a mechanism underpinning Ede1-mediated increased translation of specific mRNAs at a time when general translation is repressed.
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Affiliation(s)
- Thomas D. Williams
- MRC-PPU, School of Life Sciences, University of Dundee, Dow Street, Dundee DD5 1EH, UK
| | - Aurellia Winaya
- MRC-PPU, School of Life Sciences, University of Dundee, Dow Street, Dundee DD5 1EH, UK
| | - Ifeoluwapo Joshua
- MRC-PPU, School of Life Sciences, University of Dundee, Dow Street, Dundee DD5 1EH, UK
| | - Adrien Rousseau
- MRC-PPU, School of Life Sciences, University of Dundee, Dow Street, Dundee DD5 1EH, UK
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4
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Berg C, Sieber M, Sun J. Finishing the egg. Genetics 2024; 226:iyad183. [PMID: 38000906 PMCID: PMC10763546 DOI: 10.1093/genetics/iyad183] [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: 07/05/2023] [Accepted: 09/27/2023] [Indexed: 11/26/2023] Open
Abstract
Gamete development is a fundamental process that is highly conserved from early eukaryotes to mammals. As germ cells develop, they must coordinate a dynamic series of cellular processes that support growth, cell specification, patterning, the loading of maternal factors (RNAs, proteins, and nutrients), differentiation of structures to enable fertilization and ensure embryonic survival, and other processes that make a functional oocyte. To achieve these goals, germ cells integrate a complex milieu of environmental and developmental signals to produce fertilizable eggs. Over the past 50 years, Drosophila oogenesis has risen to the forefront as a system to interrogate the sophisticated mechanisms that drive oocyte development. Studies in Drosophila have defined mechanisms in germ cells that control meiosis, protect genome integrity, facilitate mRNA trafficking, and support the maternal loading of nutrients. Work in this system has provided key insights into the mechanisms that establish egg chamber polarity and patterning as well as the mechanisms that drive ovulation and egg activation. Using the power of Drosophila genetics, the field has begun to define the molecular mechanisms that coordinate environmental stresses and nutrient availability with oocyte development. Importantly, the majority of these reproductive mechanisms are highly conserved throughout evolution, and many play critical roles in the development of somatic tissues as well. In this chapter, we summarize the recent progress in several key areas that impact egg chamber development and ovulation. First, we discuss the mechanisms that drive nutrient storage and trafficking during oocyte maturation and vitellogenesis. Second, we examine the processes that regulate follicle cell patterning and how that patterning impacts the construction of the egg shell and the establishment of embryonic polarity. Finally, we examine regulatory factors that control ovulation, egg activation, and successful fertilization.
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Affiliation(s)
- Celeste Berg
- Department of Genome Sciences, University of Washington, Seattle, WA 98195-5065USA
| | - Matthew Sieber
- Department of Physiology, UT Southwestern Medical Center, Dallas, TX 75390USA
| | - Jianjun Sun
- Department of Physiology and Neurobiology, University of Connecticut, Storrs, CT 06269USA
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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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6
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Hussain SA, Kubo T, Hall N, Gala D, Hampson K, Parton R, Phillips MA, Wincott M, Fujita K, Davis I, Dobbie I, Booth MJ. Wavefront-sensorless adaptive optics with a laser-free spinning disk confocal microscope. J Microsc 2022; 288:106-116. [PMID: 33128278 PMCID: PMC7613844 DOI: 10.1111/jmi.12976] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2020] [Revised: 10/18/2020] [Accepted: 10/27/2020] [Indexed: 12/30/2022]
Abstract
Adaptive optics is being applied widely to a range of microscopies in order to improve imaging quality in the presence of specimen-induced aberrations. We present here the first implementation of wavefront-sensorless adaptive optics for a laser-free, aperture correlation, spinning disk microscope. This widefield method provides confocal-like optical sectioning through use of a patterned disk in the illumination and detection paths. Like other high-resolution microscopes, its operation is compromised by aberrations due to refractive index mismatch and variations within the specimen. Correction of such aberrations shows improved signal level, contrast and resolution.
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Affiliation(s)
| | - Toshiki Kubo
- Department of Applied PhysicsOsaka UniversityOsakaJapan
| | - Nicholas Hall
- Micron Advanced Bioimaging Unit, Department of BiochemistryUniversity of OxfordOxfordUK
| | - Dalia Gala
- Department of BiochemistryUniversity of OxfordOxfordUK
| | - Karen Hampson
- Department of Engineering ScienceUniversity of OxfordOxfordUK
| | | | - Mick A. Phillips
- Micron Advanced Bioimaging Unit, Department of BiochemistryUniversity of OxfordOxfordUK
| | - Matthew Wincott
- Department of Engineering ScienceUniversity of OxfordOxfordUK
| | | | - Ilan Davis
- Department of BiochemistryUniversity of OxfordOxfordUK
| | - Ian Dobbie
- Micron Advanced Bioimaging Unit, Department of BiochemistryUniversity of OxfordOxfordUK
| | - Martin J. Booth
- Department of Engineering ScienceUniversity of OxfordOxfordUK
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7
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Fang J, Lerit DA. Orb-dependent polyadenylation contributes to PLP expression and centrosome scaffold assembly. Development 2022; 149:275606. [DOI: 10.1242/dev.200426] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2021] [Accepted: 05/25/2022] [Indexed: 01/09/2023]
Abstract
ABSTRACT
As the microtubule-organizing centers of most cells, centrosomes engineer the bipolar mitotic spindle required for error-free mitosis. Drosophila Pericentrin-like protein (PLP) directs formation of a pericentriolar material (PCM) scaffold required for PCM organization and microtubule-organizing center function. Here, we investigate the post-transcriptional regulation of Plp mRNA. We identify conserved binding sites for cytoplasmic polyadenylation element binding (CPEB) proteins within the Plp 3′-untranslated region and examine the role of the CPEB ortholog Oo18 RNA-binding protein (Orb) in Plp mRNA regulation. Our data show that Orb interacts biochemically with Plp mRNA to promote polyadenylation and PLP protein expression. Loss of orb, but not orb2, diminishes PLP levels in embryonic extracts. Consequently, PLP localization to centrosomes and its function in PCM scaffolding are compromised in orb mutant embryos, resulting in genomic instability and embryonic lethality. Moreover, we find that PLP overexpression restores centrosome scaffolding and rescues the cell division defects caused by orb depletion. Our data suggest that Orb modulates PLP expression at the level of Plp mRNA polyadenylation and demonstrates that the post-transcriptional regulation of core, conserved centrosomal mRNAs is crucial for centrosome function.
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Affiliation(s)
- Junnan Fang
- Emory University School of Medicine Department of Cell Biology , , Atlanta, GA 30322 , USA
| | - Dorothy A. Lerit
- Emory University School of Medicine Department of Cell Biology , , Atlanta, GA 30322 , USA
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8
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Cochard A, Garcia-Jove Navarro M, Piroska L, Kashida S, Kress M, Weil D, Gueroui Z. RNA at the surface of phase-separated condensates impacts their size and number. Biophys J 2022; 121:1675-1690. [PMID: 35364105 PMCID: PMC9117936 DOI: 10.1016/j.bpj.2022.03.032] [Citation(s) in RCA: 13] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2021] [Revised: 01/11/2022] [Accepted: 03/28/2022] [Indexed: 11/26/2022] Open
Abstract
While it is now recognized that specific RNAs and protein families are critical for the biogenesis of ribonucleoprotein (RNP) condensates, how these molecular constituents determine condensate size and morphology is unknown. To circumvent the biochemical complexity of endogenous RNP condensates, the use of programmable tools to reconstitute condensate formation with minimal constituents can be instrumental. Here we report a methodology to form RNA-containing condensates in living cells programmed to specifically recruit a single RNA species. Our bioengineered condensates are made of ArtiGranule scaffolds composed of an orthogonal protein that can bind to a specific heterologously expressed RNA. These scaffolds undergo liquid-liquid phase separation in cells and can be chemically controlled to prevent condensation or to trigger condensate dissolution. We found that the targeted RNAs localize at the condensate surface, either as isolated RNA molecules or as a homogenous corona of RNA molecules around the condensate. The recruitment of RNA changes the material properties of condensates by hardening the condensate body. Moreover, the condensate size scales with RNA surface density; the higher the RNA density, the smaller and more frequent the condensates. These results suggest a mechanism based on physical constraints, provided by RNAs at the condensate surface, that limit condensate growth and coalescence.
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Affiliation(s)
- Audrey Cochard
- PASTEUR, Department of Chemistry, École Normale Supérieure, PSL University, Sorbonne Université, CNRS, 75005 Paris, France; Sorbonne Université, CNRS, Institut de Biologie Paris-Seine (IBPS), Laboratoire de Biologie du Développement, F-75005 Paris, France
| | - Marina Garcia-Jove Navarro
- PASTEUR, Department of Chemistry, École Normale Supérieure, PSL University, Sorbonne Université, CNRS, 75005 Paris, France
| | - Leonard Piroska
- PASTEUR, Department of Chemistry, École Normale Supérieure, PSL University, Sorbonne Université, CNRS, 75005 Paris, France
| | - Shunnichi Kashida
- PASTEUR, Department of Chemistry, École Normale Supérieure, PSL University, Sorbonne Université, CNRS, 75005 Paris, France
| | - Michel Kress
- Sorbonne Université, CNRS, Institut de Biologie Paris-Seine (IBPS), Laboratoire de Biologie du Développement, F-75005 Paris, France
| | - Dominique Weil
- Sorbonne Université, CNRS, Institut de Biologie Paris-Seine (IBPS), Laboratoire de Biologie du Développement, F-75005 Paris, France.
| | - Zoher Gueroui
- PASTEUR, Department of Chemistry, École Normale Supérieure, PSL University, Sorbonne Université, CNRS, 75005 Paris, France.
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9
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Baker FC, Neiswender H, Veeranan-Karmegam R, Gonsalvez GB. In vivo proximity biotin ligation identifies the interactome of Egalitarian, a Dynein cargo adaptor. Development 2021; 148:dev199935. [PMID: 35020877 PMCID: PMC8645207 DOI: 10.1242/dev.199935] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/25/2021] [Accepted: 10/18/2021] [Indexed: 06/21/2024]
Abstract
Numerous motors of the Kinesin family contribute to plus-end-directed microtubule transport. However, almost all transport towards the minus-end of microtubules involves Dynein. Understanding the mechanism by which Dynein transports this vast diversity of cargo is the focus of intense research. In selected cases, adaptors that link a particular cargo with Dynein have been identified. However, the sheer diversity of cargo suggests that additional adaptors must exist. We used the Drosophila egg chamber as a model to address this issue. Within egg chambers, Egalitarian is required for linking mRNA with Dynein. However, in the absence of Egalitarian, Dynein transport into the oocyte is severely compromised. This suggests that additional cargoes might be linked to Dynein in an Egalitarian-dependent manner. We therefore used proximity biotin ligation to define the interactome of Egalitarian. This approach yielded several novel interacting partners, including P body components and proteins that associate with Dynein in mammalian cells. We also devised and validated a nanobody-based proximity biotinylation strategy that can be used to define the interactome of any GFP-tagged protein.
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Affiliation(s)
| | | | | | - Graydon B. Gonsalvez
- Cellular Biology and Anatomy, Medical College of Georgia, Augusta University, 1460 Laney Walker Blvd, Augusta, GA 30912, USA
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10
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Sankaranarayanan M, Emenecker RJ, Wilby EL, Jahnel M, Trussina IREA, Wayland M, Alberti S, Holehouse AS, Weil TT. Adaptable P body physical states differentially regulate bicoid mRNA storage during early Drosophila development. Dev Cell 2021; 56:2886-2901.e6. [PMID: 34655524 PMCID: PMC8555633 DOI: 10.1016/j.devcel.2021.09.021] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2021] [Revised: 07/22/2021] [Accepted: 09/23/2021] [Indexed: 01/01/2023]
Abstract
Ribonucleoprotein condensates can exhibit diverse physical states in vitro and in vivo. Despite considerable progress, the relevance of condensate physical states for in vivo biological function remains limited. Here, we investigated the physical properties of processing bodies (P bodies) and their impact on mRNA storage in mature Drosophila oocytes. We show that the conserved DEAD-box RNA helicase Me31B forms viscous P body condensates, which adopt an arrested physical state. We demonstrate that structurally distinct proteins and protein-protein interactions, together with RNA, regulate the physical properties of P bodies. Using live imaging and in situ hybridization, we show that the arrested state and integrity of P bodies support the storage of bicoid (bcd) mRNA and that egg activation modulates P body properties, leading to the release of bcd for translation in the early embryo. Together, this work provides an example of how physical states of condensates regulate cellular function in development.
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Affiliation(s)
- M Sankaranarayanan
- Department of Zoology, University of Cambridge, Downing Street, Cambridge CB2 3EJ, UK.
| | - Ryan J Emenecker
- Department of Biochemistry and Molecular Biophysics, Washington University School of Medicine, 660 S. Euclid Ave., St. Louis, MO 63110, USA; Center for Science and Engineering of Living Systems, Washington University in St. Louis, 1 Brookings Drive, St. Louis, MO 63130, USA
| | - Elise L Wilby
- Department of Zoology, University of Cambridge, Downing Street, Cambridge CB2 3EJ, UK
| | - Marcus Jahnel
- Center for Molecular and Cellular Bioengineering, Biotechnology Center, Technische Universität Dresden, Tatzberg 47/49, 01307 Dresden, Germany
| | - Irmela R E A Trussina
- Center for Molecular and Cellular Bioengineering, Biotechnology Center, Technische Universität Dresden, Tatzberg 47/49, 01307 Dresden, Germany
| | - Matt Wayland
- Department of Zoology, University of Cambridge, Downing Street, Cambridge CB2 3EJ, UK
| | - Simon Alberti
- Center for Molecular and Cellular Bioengineering, Biotechnology Center, Technische Universität Dresden, Tatzberg 47/49, 01307 Dresden, Germany
| | - Alex S Holehouse
- Department of Biochemistry and Molecular Biophysics, Washington University School of Medicine, 660 S. Euclid Ave., St. Louis, MO 63110, USA; Center for Science and Engineering of Living Systems, Washington University in St. Louis, 1 Brookings Drive, St. Louis, MO 63130, USA
| | - Timothy T Weil
- Department of Zoology, University of Cambridge, Downing Street, Cambridge CB2 3EJ, UK.
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11
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Hecw controls oogenesis and neuronal homeostasis by promoting the liquid state of ribonucleoprotein particles. Nat Commun 2021; 12:5488. [PMID: 34531401 PMCID: PMC8446043 DOI: 10.1038/s41467-021-25809-8] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/24/2020] [Accepted: 08/31/2021] [Indexed: 01/17/2023] Open
Abstract
Specialised ribonucleoprotein (RNP) granules are a hallmark of polarized cells, like neurons and germ cells. Among their main functions is the spatial and temporal modulation of the activity of specific mRNA transcripts that allow specification of primary embryonic axes. While RNPs composition and role are well established, their regulation is poorly defined. Here, we demonstrate that Hecw, a newly identified Drosophila ubiquitin ligase, is a key modulator of RNPs in oogenesis and neurons. Hecw depletion leads to the formation of enlarged granules that transition from a liquid to a gel-like state. Loss of Hecw activity results in defective oogenesis, premature aging and climbing defects associated with neuronal loss. At the molecular level, reduced ubiquitination of the Fmrp impairs its translational repressor activity, resulting in altered Orb expression in nurse cells and Profilin in neurons. Ribonucleoprotein (RNP) granules are responsible for mRNA transport and local translation required for neuronal and oocyte maturation. Here the authors show that loss of the Drosophila Ub ligase Hecw enlarges RNP granules, leads to a liquid to gel-like transition, and results in defective oogenesis and neuronal loss.
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12
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The multiscale and multiphase organization of the transcriptome. Emerg Top Life Sci 2021; 4:265-280. [PMID: 32542380 DOI: 10.1042/etls20190187] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2020] [Revised: 05/08/2020] [Accepted: 05/18/2020] [Indexed: 02/06/2023]
Abstract
Gene expression must be co-ordinated to cellular activity. From transcription to decay, the expression of millions of RNA molecules is highly synchronized. RNAs are covered by proteins that regulate every aspect of their cellular life: expression, storage, translational status, localization, and decay. Many RNAs and their associated regulatory proteins can coassemble to condense into liquid droplets, viscoelastic hydrogels, freeze into disorganized glass-like aggregates, or harden into quasi-crystalline solids. Phase separations provide a framework for transcriptome organization where the single functional unit is no longer a transcript but instead an RNA regulon. Here, we will analyze the interaction networks that underlie RNA super-assemblies, assess the complex multiscale, multiphase architecture of the transcriptome, and explore how the biophysical state of an RNA molecule can define its fate. Phase separations are emerging as critical routes for the epitranscriptomic control of gene expression.
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13
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Shlemov A, Alexandrov T, Golyandina N, Holloway D, Baumgartner S, Spirov AV. Quantification reveals early dynamics in Drosophila maternal gradients. PLoS One 2021; 16:e0244701. [PMID: 34411119 PMCID: PMC8376041 DOI: 10.1371/journal.pone.0244701] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/12/2020] [Accepted: 07/16/2021] [Indexed: 11/18/2022] Open
Abstract
The Bicoid (Bcd) protein is a primary determinant of early anterior-posterior (AP) axis specification in Drosophila embryogenesis. This morphogen is spatially distributed in an anterior-high gradient, and affects particular AP cell fates in a concentration-dependent manner. The early distribution and dynamics of the bicoid (bcd) mRNA, the source for the Bcd protein gradient, is not well understood, leaving a number of open questions for how Bcd positional information develops and is regulated. Confocal microscope images of whole early embryos, stained for bcd mRNA or the Staufen (Stau) protein involved in its transport, were processed to extract quantitative AP intensity profiles at two depths (apical-under the embryo surface but above the nuclear layer; and basal-below the nuclei). Each profile was quantified by a two- (or three-) exponential equation. The parameters of these equations were used to analyze the early developmental dynamics of bcd. Analysis of 1D profiles was compared with 2D intensity surfaces from the same images. This approach reveals strong early changes in bcd and Stau, which appear to be coordinated. We can unambiguously discriminate three stages in early development using the exponential parameters: pre-blastoderm (1-9 cleavage cycle, cc), syncytial blastoderm (10-13 cc) and cellularization (from 14A cc). Key features which differ in this period are how fast the first exponential (anterior component) of the apical profile drops with distance and whether it is higher or lower than the basal first exponential. We can further discriminate early and late embryos within the pre-blastoderm stage, depending on how quickly the anterior exponential drops. This relates to the posterior-wards spread of bcd in the first hour of development. Both bcd and Stau show several redistributions in the head cytoplasm, quite probably related to nuclear activity: first shifting inwards towards the core plasm, forming either protrusions (early pre-blastoderm) or round aggregations (early nuclear cleavage cycles, cc, 13 and 14), then moving to the embryo surface and spreading posteriorly. These movements are seen both with the 2D surface study and the 1D profile analysis. The continued spreading of bcd can be tracked from the time of nuclear layer formation (later pre-blastoderm) to the later syncytial blastoderm stages by the progressive loss of steepness of the apical anterior exponential (for both bcd and Stau). Finally, at the beginning of cc14 (cellularization stage) we see a distinctive flip from the basal anterior gradient being higher to the apical gradient being higher (for both bcd and Stau). Quantitative analysis reveals substantial (and correlated) bcd and Stau redistributions during early development, supporting that the distribution and dynamics of bcd mRNA are key factors in the formation and maintenance of the Bcd protein morphogenetic gradient. This analysis reveals the complex and dynamic nature of bcd redistribution, particularly in the head cytoplasm. These resemble observations in oogenesis; their role and significance have yet to be clarified. The observed co-localization during redistribution of bcd and Stau may indicate the involvement of active transport.
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Affiliation(s)
- Alex Shlemov
- Laboratory for Algorithmic Biology, St. Petersburg State University, St. Petersburg, Russia
| | - Theodore Alexandrov
- Structural and Computational Biology Unit, European Molecular Biology Laboratory, Heidelberg, Germany
- Skaggs School of Pharmacy and Pharmaceutical Sciences, University of California San Diego, La Jolla, California, United States of America
| | - Nina Golyandina
- Faculty of Mathematics and Mechanics, St. Petersburg State University, St. Petersburg, Russia
| | - David Holloway
- Mathematics Department, British Columbia Institute of Technology, Burnaby, British Columbia, Canada
| | - Stefan Baumgartner
- Department of Experimental Medical Sciences, Lund University, Lund, Sweden
- Department of Biology, University of Konstanz, Konstanz, Germany
| | - Alexander V. Spirov
- Computer Science and CEWIT, SUNY Stony Brook, Stony Brook, New York, United States of America
- Lab Modelling Evolution, The I.M. Sechenov Institute of Evolutionary Physiology & Biochemistry, St. Petersburg, Russia
- * E-mail:
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14
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Lashkevich KA, Dmitriev SE. mRNA Targeting, Transport and Local Translation in Eukaryotic Cells: From the Classical View to a Diversity of New Concepts. Mol Biol 2021; 55:507-537. [PMID: 34092811 PMCID: PMC8164833 DOI: 10.1134/s0026893321030080] [Citation(s) in RCA: 28] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2021] [Revised: 02/26/2021] [Accepted: 03/12/2021] [Indexed: 12/28/2022]
Abstract
Spatial organization of protein biosynthesis in the eukaryotic cell has been studied for more than fifty years, thus many facts have already been included in textbooks. According to the classical view, mRNA transcripts encoding secreted and transmembrane proteins are translated by ribosomes associated with endoplasmic reticulum membranes, while soluble cytoplasmic proteins are synthesized on free polysomes. However, in the last few years, new data has emerged, revealing selective translation of mRNA on mitochondria and plastids, in proximity to peroxisomes and endosomes, in various granules and at the cytoskeleton (actin network, vimentin intermediate filaments, microtubules and centrosomes). There are also long-standing debates about the possibility of protein synthesis in the nucleus. Localized translation can be determined by targeting signals in the synthesized protein, nucleotide sequences in the mRNA itself, or both. With RNA-binding proteins, many transcripts can be assembled into specific RNA condensates and form RNP particles, which may be transported by molecular motors to the sites of active translation, form granules and provoke liquid-liquid phase separation in the cytoplasm, both under normal conditions and during cell stress. The translation of some mRNAs occurs in specialized "translation factories," assemblysomes, transperons and other structures necessary for the correct folding of proteins, interaction with functional partners and formation of oligomeric complexes. Intracellular localization of mRNA has a significant impact on the efficiency of its translation and presumably determines its response to cellular stress. Compartmentalization of mRNAs and the translation machinery also plays an important role in viral infections. Many viruses provoke the formation of specific intracellular structures, virus factories, for the production of their proteins. Here we review the current concepts of the molecular mechanisms of transport, selective localization and local translation of cellular and viral mRNAs, their effects on protein targeting and topogenesis, and on the regulation of protein biosynthesis in different compartments of the eukaryotic cell. Special attention is paid to new systems biology approaches, providing new cues to the study of localized translation.
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Affiliation(s)
- Kseniya A Lashkevich
- Belozersky Institute of Physico-Chemical Biology, Moscow State University, 119234 Moscow, Russia.,Faculty of Bioengineering and Bioinformatics, Moscow State University, 119234 Moscow, Russia
| | - Sergey E Dmitriev
- Belozersky Institute of Physico-Chemical Biology, Moscow State University, 119234 Moscow, Russia.,Faculty of Bioengineering and Bioinformatics, Moscow State University, 119234 Moscow, Russia.,Engelhardt Institute of Molecular Biology, Russian Academy of Sciences, 119991 Moscow, Russia
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15
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Mediani L, Antoniani F, Galli V, Vinet J, Carrà AD, Bigi I, Tripathy V, Tiago T, Cimino M, Leo G, Amen T, Kaganovich D, Cereda C, Pansarasa O, Mandrioli J, Tripathi P, Troost D, Aronica E, Buchner J, Goswami A, Sterneckert J, Alberti S, Carra S. Hsp90-mediated regulation of DYRK3 couples stress granule disassembly and growth via mTORC1 signaling. EMBO Rep 2021; 22:e51740. [PMID: 33738926 PMCID: PMC8097338 DOI: 10.15252/embr.202051740] [Citation(s) in RCA: 31] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/17/2020] [Revised: 02/02/2021] [Accepted: 02/19/2021] [Indexed: 12/24/2022] Open
Abstract
Stress granules (SGs) are dynamic condensates associated with protein misfolding diseases. They sequester stalled mRNAs and signaling factors, such as the mTORC1 subunit raptor, suggesting that SGs coordinate cell growth during and after stress. However, the molecular mechanisms linking SG dynamics and signaling remain undefined. We report that the chaperone Hsp90 is required for SG dissolution. Hsp90 binds and stabilizes the dual‐specificity tyrosine‐phosphorylation‐regulated kinase 3 (DYRK3) in the cytosol. Upon Hsp90 inhibition, DYRK3 dissociates from Hsp90 and becomes inactive. Inactive DYRK3 is subjected to two different fates: it either partitions into SGs, where it is protected from irreversible aggregation, or it is degraded. In the presence of Hsp90, DYRK3 is active and promotes SG disassembly, restoring mTORC1 signaling and translation. Thus, Hsp90 links stress adaptation and cell growth by regulating the activity of a key kinase involved in condensate disassembly and translation restoration.
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Affiliation(s)
- Laura Mediani
- Department of Biomedical, Metabolic and Neural Sciences, Centre for Neuroscience and Nanotechnology, University of Modena and Reggio Emilia, Modena, Italy
| | - Francesco Antoniani
- Department of Biomedical, Metabolic and Neural Sciences, Centre for Neuroscience and Nanotechnology, University of Modena and Reggio Emilia, Modena, Italy
| | - Veronica Galli
- Department of Biomedical, Metabolic and Neural Sciences, Centre for Neuroscience and Nanotechnology, University of Modena and Reggio Emilia, Modena, Italy
| | - Jonathan Vinet
- Department of Biomedical, Metabolic and Neural Sciences, Centre for Neuroscience and Nanotechnology, University of Modena and Reggio Emilia, Modena, Italy.,Genomic and Post-Genomic Center, IRCCS Mondino Foundation, Pavia, Italy
| | - Arianna Dorotea Carrà
- Department of Biomedical, Metabolic and Neural Sciences, Centre for Neuroscience and Nanotechnology, University of Modena and Reggio Emilia, Modena, Italy
| | - Ilaria Bigi
- Department of Biomedical, Metabolic and Neural Sciences, Centre for Neuroscience and Nanotechnology, University of Modena and Reggio Emilia, Modena, Italy
| | - Vadreenath Tripathy
- Center for Regenerative Therapies TU Dresden, Technische Universität Dresden, Dresden, Germany
| | - Tatiana Tiago
- Department of Biomedical, Metabolic and Neural Sciences, Centre for Neuroscience and Nanotechnology, University of Modena and Reggio Emilia, Modena, Italy
| | - Marco Cimino
- Department of Biomedical, Metabolic and Neural Sciences, Centre for Neuroscience and Nanotechnology, University of Modena and Reggio Emilia, Modena, Italy
| | - Giuseppina Leo
- Department of Biomedical, Metabolic and Neural Sciences, Centre for Neuroscience and Nanotechnology, University of Modena and Reggio Emilia, Modena, Italy
| | - Triana Amen
- Department of Experimental Neurodegeneration, University Medical Center Göttingen, Göttingen, Germany
| | - Daniel Kaganovich
- Department of Experimental Neurodegeneration, University Medical Center Göttingen, Göttingen, Germany
| | - Cristina Cereda
- Genomic and Post-Genomic Center, IRCCS Mondino Foundation, Pavia, Italy
| | - Orietta Pansarasa
- Genomic and Post-Genomic Center, IRCCS Mondino Foundation, Pavia, Italy
| | - Jessica Mandrioli
- Department of Neuroscience, St. Agostino Estense Hospital, Azienda Ospedaliero Universitaria di Modena, Modena, Italy
| | - Priyanka Tripathi
- Institute of Neuropathology, RWTH Aachen University Hospital, Aachen, Germany
| | - Dirk Troost
- Department of (Neuro)Pathology, Amsterdam Neuroscience, Amsterdam UMC, University of Amsterdam, Amsterdam, The Netherlands
| | - Eleonora Aronica
- Department of (Neuro)Pathology, Amsterdam Neuroscience, Amsterdam UMC, University of Amsterdam, Amsterdam, The Netherlands
| | - Johannes Buchner
- Center for Integrated Protein Science Munich at the Department Chemie, Technische Universität München, Garching, Germany
| | - Anand Goswami
- Institute of Neuropathology, RWTH Aachen University Hospital, Aachen, Germany
| | - Jared Sterneckert
- Center for Regenerative Therapies TU Dresden, Technische Universität Dresden, Dresden, Germany
| | - Simon Alberti
- Biotechnology Center (BIOTEC), Center for Molecular and Cellular Bioengineering (CMCB), Technische Universität Dresden, Dresden, Germany
| | - Serena Carra
- Department of Biomedical, Metabolic and Neural Sciences, Centre for Neuroscience and Nanotechnology, University of Modena and Reggio Emilia, Modena, Italy
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16
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Mateju D, Eichenberger B, Voigt F, Eglinger J, Roth G, Chao JA. Single-Molecule Imaging Reveals Translation of mRNAs Localized to Stress Granules. Cell 2020; 183:1801-1812.e13. [PMID: 33308477 DOI: 10.1016/j.cell.2020.11.010] [Citation(s) in RCA: 153] [Impact Index Per Article: 38.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2020] [Revised: 09/14/2020] [Accepted: 11/05/2020] [Indexed: 12/22/2022]
Abstract
Cellular stress leads to reprogramming of mRNA translation and formation of stress granules (SGs), membraneless organelles consisting of mRNA and RNA-binding proteins. Although the function of SGs remains largely unknown, it is widely assumed they contain exclusively non-translating mRNA. Here, we re-examine this hypothesis using single-molecule imaging of mRNA translation in living cells. Although we observe non-translating mRNAs are preferentially recruited to SGs, we find unequivocal evidence that mRNAs localized to SGs can undergo translation. Our data indicate that SG-associated translation is not rare, and the entire translation cycle (initiation, elongation, and termination) can occur on SG-localized transcripts. Furthermore, translating mRNAs can be observed transitioning between the cytosol and SGs without changing their translational status. Together, these results demonstrate that mRNA localization to SGs is compatible with translation and argue against a direct role for SGs in inhibition of protein synthesis.
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Affiliation(s)
- Daniel Mateju
- Friedrich Miescher Institute for Biomedical Research, 4058 Basel, Switzerland
| | - Bastian Eichenberger
- Friedrich Miescher Institute for Biomedical Research, 4058 Basel, Switzerland; University of Basel, 4003 Basel, Switzerland
| | - Franka Voigt
- Friedrich Miescher Institute for Biomedical Research, 4058 Basel, Switzerland
| | - Jan Eglinger
- Friedrich Miescher Institute for Biomedical Research, 4058 Basel, Switzerland
| | - Gregory Roth
- Friedrich Miescher Institute for Biomedical Research, 4058 Basel, Switzerland
| | - Jeffrey A Chao
- Friedrich Miescher Institute for Biomedical Research, 4058 Basel, Switzerland.
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17
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Rathore OS, Silva RD, Ascensão-Ferreira M, Matos R, Carvalho C, Marques B, Tiago MN, Prudêncio P, Andrade RP, Roignant JY, Barbosa-Morais NL, Martinho RG. NineTeen Complex-subunit Salsa is required for efficient splicing of a subset of introns and dorsal-ventral patterning. RNA (NEW YORK, N.Y.) 2020; 26:1935-1956. [PMID: 32963109 PMCID: PMC7668242 DOI: 10.1261/rna.077446.120] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 08/12/2020] [Accepted: 09/07/2020] [Indexed: 06/11/2023]
Abstract
The NineTeen Complex (NTC), also known as pre-mRNA-processing factor 19 (Prp19) complex, regulates distinct spliceosome conformational changes necessary for splicing. During Drosophila midblastula transition, splicing is particularly sensitive to mutations in NTC-subunit Fandango, which suggests differential requirements of NTC during development. We show that NTC-subunit Salsa, the Drosophila ortholog of human RNA helicase Aquarius, is rate-limiting for splicing of a subset of small first introns during oogenesis, including the first intron of gurken Germline depletion of Salsa and splice site mutations within gurken first intron impair both adult female fertility and oocyte dorsal-ventral patterning, due to an abnormal expression of Gurken. Supporting causality, the fertility and dorsal-ventral patterning defects observed after Salsa depletion could be suppressed by the expression of a gurken construct without its first intron. Altogether, our results suggest that one of the key rate-limiting functions of Salsa during oogenesis is to ensure the correct expression and efficient splicing of the first intron of gurken mRNA. Retention of gurken first intron compromises the function of this gene most likely because it undermines the correct structure and function of the transcript 5'UTR.
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Affiliation(s)
- Om Singh Rathore
- Center for Biomedical Research (CBMR), Universidade do Algarve, Faro, 8005-139 Portugal
| | - Rui D Silva
- Center for Biomedical Research (CBMR), Universidade do Algarve, Faro, 8005-139 Portugal
| | - Mariana Ascensão-Ferreira
- Instituto de Medicina Molecular João Lobo Antunes, Faculdade de Medicina, Universidade de Lisboa, 1649-028 Lisboa, Portugal
| | - Ricardo Matos
- Center for Biomedical Research (CBMR), Universidade do Algarve, Faro, 8005-139 Portugal
| | - Célia Carvalho
- Instituto de Medicina Molecular João Lobo Antunes, Faculdade de Medicina, Universidade de Lisboa, 1649-028 Lisboa, Portugal
| | - Bruno Marques
- Center for Biomedical Research (CBMR), Universidade do Algarve, Faro, 8005-139 Portugal
| | - Margarida N Tiago
- Center for Biomedical Research (CBMR), Universidade do Algarve, Faro, 8005-139 Portugal
| | - Pedro Prudêncio
- Center for Biomedical Research (CBMR), Universidade do Algarve, Faro, 8005-139 Portugal
- Instituto de Medicina Molecular João Lobo Antunes, Faculdade de Medicina, Universidade de Lisboa, 1649-028 Lisboa, Portugal
| | - Raquel P Andrade
- Center for Biomedical Research (CBMR), Universidade do Algarve, Faro, 8005-139 Portugal
- Department of Medicine and Biomedical Sciences and Algarve Biomedical Center, Universidade do Algarve, 8005-139 Faro, Portugal
| | - Jean-Yves Roignant
- Center for Integrative Genomics, Faculty of Biology and Medicine, University of Lausanne, CH-1015 Lausanne, Switzerland
- Institute of Pharmaceutical and Biomedical Sciences, Johannes Gutenberg-University Mainz, 55128 Mainz, Germany
| | - Nuno L Barbosa-Morais
- Instituto de Medicina Molecular João Lobo Antunes, Faculdade de Medicina, Universidade de Lisboa, 1649-028 Lisboa, Portugal
| | - Rui Gonçalo Martinho
- Center for Biomedical Research (CBMR), Universidade do Algarve, Faro, 8005-139 Portugal
- Instituto de Medicina Molecular João Lobo Antunes, Faculdade de Medicina, Universidade de Lisboa, 1649-028 Lisboa, Portugal
- Department of Medical Sciences and Institute for Biomedicine (iBiMED), Universidade de Aveiro, 3810-193 Aveiro, Portugal
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18
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Kulkarni A, Lopez DH, Extavour CG. Shared Cell Biological Functions May Underlie Pleiotropy of Molecular Interactions in the Germ Lines and Nervous Systems of Animals. Front Ecol Evol 2020. [DOI: 10.3389/fevo.2020.00215] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023] Open
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19
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Huggins HP, Keiper BD. Regulation of Germ Cell mRNPs by eIF4E:4EIP Complexes: Multiple Mechanisms, One Goal. Front Cell Dev Biol 2020; 8:562. [PMID: 32733883 PMCID: PMC7358283 DOI: 10.3389/fcell.2020.00562] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/24/2020] [Accepted: 06/15/2020] [Indexed: 11/29/2022] Open
Abstract
Translational regulation of mRNAs is critically important for proper gene expression in germ cells, gametes, and embryos. The ability of the nucleus to control gene expression in these systems may be limited due to spatial or temporal constraints, as well as the breadth of gene products they express to prepare for the rapid animal development that follows. During development germ granules are hubs of post-transcriptional regulation of mRNAs. They assemble and remodel messenger ribonucleoprotein (mRNP) complexes for translational repression or activation. Recently, mRNPs have been appreciated as discrete regulatory units, whose function is dictated by the many positive and negative acting factors within the complex. Repressed mRNPs must be activated for translation on ribosomes to introduce novel proteins into germ cells. The binding of eIF4E to interacting proteins (4EIPs) that sequester it represents a node that controls many aspects of mRNP fate including localization, stability, poly(A) elongation, deadenylation, and translational activation/repression. Furthermore, plants and animals have evolved to express multiple functionally distinct eIF4E and 4EIP variants within germ cells, giving rise to different modes of translational regulation.
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Affiliation(s)
- Hayden P Huggins
- Department of Biochemistry and Molecular Biology, Brody School of Medicine, East Carolina University, Greenville, NC, United States
| | - Brett D Keiper
- Department of Biochemistry and Molecular Biology, Brody School of Medicine, East Carolina University, Greenville, NC, United States
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20
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Harrison JU, Parton RM, Davis I, Baker RE. Testing Models of mRNA Localization Reveals Robustness Regulated by Reducing Transport between Cells. Biophys J 2019; 117:2154-2165. [PMID: 31708163 PMCID: PMC6895595 DOI: 10.1016/j.bpj.2019.10.025] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2019] [Revised: 09/18/2019] [Accepted: 10/15/2019] [Indexed: 11/26/2022] Open
Abstract
Robust control of gene expression in both space and time is of central importance in the regulation of cellular processes and for multicellular development. However, the mechanisms by which robustness is achieved are generally not identified or well understood. For example, messenger RNA (mRNA) localization by molecular motor-driven transport is crucial for cell polarization in numerous contexts, but the regulatory mechanisms that enable this process to take place in the face of noise or significant perturbations are not fully understood. Here, we use a combined experimental-theoretical approach to characterize the robustness of gurken/transforming growth factor-α mRNA localization in Drosophila egg chambers, where the oocyte and 15 surrounding nurse cells are connected in a stereotypic network via intracellular bridges known as ring canals. We construct a mathematical model that encodes simplified descriptions of the range of steps involved in mRNA localization, including production and transport between and within cells until the final destination in the oocyte. Using Bayesian inference, we calibrate this model using quantitative single molecule fluorescence in situ hybridization data. By analyzing both the steady state and dynamic behaviors of the model, we provide estimates for the rates of different steps of the localization process as well as the extent of directional bias in transport through the ring canals. The model predicts that mRNA synthesis and transport must be tightly balanced to maintain robustness, a prediction that we tested experimentally using an overexpression mutant. Surprisingly, the overexpression mutant fails to display the anticipated degree of overaccumulation of mRNA in the oocyte predicted by the model. Through careful model-based analysis of quantitative data from the overexpression mutant, we show evidence of saturation of the transport of mRNA through ring canals. We conclude that this saturation engenders robustness of the localization process in the face of significant variation in the levels of mRNA synthesis.
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Affiliation(s)
- Jonathan U Harrison
- Zeeman Institute, Mathematical Institute, University of Warwick, Coventry, United Kingdom; Wolfson Centre for Mathematical Biology, Mathematical Institute, University of Oxford, Oxford, United Kingdom.
| | - Richard M Parton
- Department of Biochemistry, University of Oxford, Oxford, United Kingdom
| | - Ilan Davis
- Department of Biochemistry, University of Oxford, Oxford, United Kingdom
| | - Ruth E Baker
- Wolfson Centre for Mathematical Biology, Mathematical Institute, University of Oxford, Oxford, United Kingdom
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21
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van Leeuwen W, Rabouille C. Cellular stress leads to the formation of membraneless stress assemblies in eukaryotic cells. Traffic 2019; 20:623-638. [PMID: 31152627 PMCID: PMC6771618 DOI: 10.1111/tra.12669] [Citation(s) in RCA: 42] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2019] [Revised: 05/10/2019] [Accepted: 05/30/2019] [Indexed: 12/28/2022]
Abstract
In cells at steady state, two forms of cell compartmentalization coexist: membrane-bound organelles and phase-separated membraneless organelles that are present in both the nucleus and the cytoplasm. Strikingly, cellular stress is a strong inducer of the reversible membraneless compartments referred to as stress assemblies. Stress assemblies play key roles in survival during cell stress and in thriving of cells upon stress relief. The two best studied stress assemblies are the RNA-based processing-bodies (P-bodies) and stress granules that form in response to oxidative, endoplasmic reticulum (ER), osmotic and nutrient stress as well as many others. Interestingly, P-bodies and stress granules are heterogeneous with respect to both the pathways that lead to their formation and their protein and RNA content. Furthermore, in yeast and Drosophila, nutrient stress also leads to the formation of many other types of prosurvival cytoplasmic stress assemblies, such as metabolic enzymes foci, proteasome storage granules, EIF2B bodies, U-bodies and Sec bodies, some of which are not RNA-based. Nutrient stress leads to a drop in cytoplasmic pH, which combined with posttranslational modifications of granule contents, induces phase separation.
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Affiliation(s)
- Wessel van Leeuwen
- Hubrecht Institute of the Royal Netherlands Academy of Arts and Sciencesand University Medical Center UtrechtUtrechtthe Netherlands
| | - Catherine Rabouille
- Hubrecht Institute of the Royal Netherlands Academy of Arts and Sciencesand University Medical Center UtrechtUtrechtthe Netherlands
- Department of Biomedical Science of Cells and SystemsUniversity Medical Center GroningenGroningenthe Netherlands
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22
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Teixeira FK, Lehmann R. Translational Control during Developmental Transitions. Cold Spring Harb Perspect Biol 2019; 11:cshperspect.a032987. [PMID: 30082467 DOI: 10.1101/cshperspect.a032987] [Citation(s) in RCA: 42] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
The many steps of gene expression, from the transcription of a gene to the production of its protein product, are well understood. Yet, transcriptional regulation has been the focal point for the study of gene expression during development. However, quantitative studies reveal that messenger RNA (mRNA) levels are not necessarily good predictors of the respective proteins' levels in a cell. This discrepancy is, at least in part, the result of developmentally regulated, translational mechanisms that control the spatiotemporal regulation of gene expression. In this review, we focus on translational regulatory mechanisms mediating global transitions in gene expression: the shift from the maternal to the embryonic developmental program in the early embryo and the switch from the self-renewal of stem cells to differentiation in the adult.
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Affiliation(s)
| | - Ruth Lehmann
- Howard Hughes Medical Institute (HHMI) and Kimmel Center for Biology and Medicine of the Skirball Institute, Department of Cell Biology, New York University School of Medicine, New York, New York 10016
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23
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Subcellular Specialization and Organelle Behavior in Germ Cells. Genetics 2018; 208:19-51. [PMID: 29301947 DOI: 10.1534/genetics.117.300184] [Citation(s) in RCA: 34] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/25/2016] [Accepted: 08/17/2017] [Indexed: 11/18/2022] Open
Abstract
Gametes, eggs and sperm, are the highly specialized cell types on which the development of new life solely depends. Although all cells share essential organelles, such as the ER (endoplasmic reticulum), Golgi, mitochondria, and centrosomes, germ cells display unique regulation and behavior of organelles during gametogenesis. These germ cell-specific functions of organelles serve critical roles in successful gamete production. In this chapter, I will review the behaviors and roles of organelles during germ cell differentiation.
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24
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Wang C, Schmich F, Srivatsa S, Weidner J, Beerenwinkel N, Spang A. Context-dependent deposition and regulation of mRNAs in P-bodies. eLife 2018; 7:29815. [PMID: 29297464 PMCID: PMC5752201 DOI: 10.7554/elife.29815] [Citation(s) in RCA: 50] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2017] [Accepted: 12/13/2017] [Indexed: 12/21/2022] Open
Abstract
Cells respond to stress by remodeling their transcriptome through transcription and degradation. Xrn1p-dependent degradation in P-bodies is the most prevalent decay pathway, yet, P-bodies may facilitate not only decay, but also act as a storage compartment. However, which and how mRNAs are selected into different degradation pathways and what determines the fate of any given mRNA in P-bodies remain largely unknown. We devised a new method to identify both common and stress-specific mRNA subsets associated with P-bodies. mRNAs targeted for degradation to P-bodies, decayed with different kinetics. Moreover, the localization of a specific set of mRNAs to P-bodies under glucose deprivation was obligatory to prevent decay. Depending on its client mRNA, the RNA-binding protein Puf5p either promoted or inhibited decay. Furthermore, the Puf5p-dependent storage of a subset of mRNAs in P-bodies under glucose starvation may be beneficial with respect to chronological lifespan.
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Affiliation(s)
- Congwei Wang
- Growth and Development, Biozentrum, University of Basel, Basel, Switzerland
| | - Fabian Schmich
- Department of Biosystems Science and Engineering, ETH Zürich, Basel, Switzerland.,Swiss Institute of Bioinformatics, Basel, Switzerland
| | - Sumana Srivatsa
- Department of Biosystems Science and Engineering, ETH Zürich, Basel, Switzerland.,Swiss Institute of Bioinformatics, Basel, Switzerland
| | - Julie Weidner
- Growth and Development, Biozentrum, University of Basel, Basel, Switzerland
| | - Niko Beerenwinkel
- Department of Biosystems Science and Engineering, ETH Zürich, Basel, Switzerland.,Swiss Institute of Bioinformatics, Basel, Switzerland
| | - Anne Spang
- Growth and Development, Biozentrum, University of Basel, Basel, Switzerland
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25
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Duhart JC, Parsons TT, Raftery LA. The repertoire of epithelial morphogenesis on display: Progressive elaboration of Drosophila egg structure. Mech Dev 2017; 148:18-39. [PMID: 28433748 DOI: 10.1016/j.mod.2017.04.002] [Citation(s) in RCA: 52] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/03/2017] [Revised: 04/07/2017] [Accepted: 04/12/2017] [Indexed: 12/26/2022]
Abstract
Epithelial structures are foundational for tissue organization in all metazoans. Sheets of epithelial cells form lateral adhesive junctions and acquire apico-basal polarity perpendicular to the surface of the sheet. Genetic analyses in the insect model, Drosophila melanogaster, have greatly advanced our understanding of how epithelial organization is established, and how it is modulated during tissue morphogenesis. Major insights into collective cell migrations have come from analyses of morphogenetic movements within the adult follicular epithelium that cooperates with female germ cells to build a mature egg. Epithelial follicle cells progress through tightly choreographed phases of proliferation, patterning, reorganization and migrations, before they differentiate to form the elaborate structures of the eggshell. Distinct structural domains are organized by differential adhesion, within which lateral junctions are remodeled to further shape the organized epithelia. During collective cell migrations, adhesive interactions mediate supracellular organization of planar polarized macromolecules, and facilitate crawling over the basement membrane or traction against adjacent cell surfaces. Comparative studies with other insects are revealing the diversification of morphogenetic movements for elaboration of epithelial structures. This review surveys the repertoire of follicle cell morphogenesis, to highlight the coordination of epithelial plasticity with progressive differentiation of a secretory epithelium. Technological advances will keep this tissue at the leading edge for interrogating the precise spatiotemporal regulation of normal epithelial reorganization events, and provide a framework for understanding pathological tissue dysplasia.
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Affiliation(s)
- Juan Carlos Duhart
- School of Life Sciences, University of Nevada, Las Vegas, 4505 S. Maryland Parkway, Las Vegas, NV 89154-4004, United States
| | - Travis T Parsons
- School of Life Sciences, University of Nevada, Las Vegas, 4505 S. Maryland Parkway, Las Vegas, NV 89154-4004, United States
| | - Laurel A Raftery
- School of Life Sciences, University of Nevada, Las Vegas, 4505 S. Maryland Parkway, Las Vegas, NV 89154-4004, United States.
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26
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Aguilera-Gomez A, Rabouille C. Membrane-bound organelles versus membrane-less compartments and their control of anabolic pathways in Drosophila. Dev Biol 2017; 428:310-317. [PMID: 28377034 DOI: 10.1016/j.ydbio.2017.03.029] [Citation(s) in RCA: 36] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/03/2017] [Revised: 03/27/2017] [Accepted: 03/27/2017] [Indexed: 12/29/2022]
Abstract
Classically, we think of cell compartmentalization as being achieved by membrane-bound organelles. It has nevertheless emerged that membrane-less assemblies also largely contribute to this compartmentalization. Here, we compare the characteristics of both types of compartmentalization in term of maintenance of functional identities. Furthermore, membrane less-compartments are critical for sustaining developmental and cell biological events as they control major metabolic pathways. We describe two examples related to this issue in Drosophila, the role of P-bodies in the translational control of gurken in the Drosophila oocyte, and the formation of Sec bodies upon amino-acid starvation in Drosophila cells.
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Affiliation(s)
| | - Catherine Rabouille
- Hubrecht Institute of the KNAW & UMC Utrecht, 3584 CT Utrecht, The Netherlands; Department of Cell Biology, UMC Utrecht, The Netherlands; Department of Cell Biology, UMC Groningen, The Netherlands.
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27
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Abstract
Acquisition of oocyte polarity involves complex translocation and aggregation of intracellular organelles, RNAs, and proteins, along with strict posttranscriptional regulation. While much is still unknown regarding the formation of the animal-vegetal axis, an early marker of polarity, animal models have contributed to our understanding of these early processes controlling normal oogenesis and embryo development. In recent years, it has become clear that proteins with self-assembling properties are involved in assembling discrete subcellular compartments or domains underlying subcellular asymmetries in the early mitotic and meiotic cells of the female germline. These include asymmetries in duplication of the centrioles and formation of centrosomes and assembly of the organelle and RNA-rich Balbiani body, which plays a critical role in oocyte polarity. Notably, at specific stages of germline development, these transient structures in oocytes are temporally coincident and align with asymmetries in the position and arrangement of nuclear components, such as the nuclear pore and the chromosomal bouquet and the centrioles and cytoskeleton in the cytoplasm. Formation of these critical, transient structures and arrangements involves microtubule pathways, intrinsically disordered proteins (proteins with domains that tend to be fluid or lack a rigid ordered three-dimensional structure ranging from random coils, globular domains, to completely unstructured proteins), and translational repressors and activators. This review aims to examine recent literature and key players in oocyte polarity.
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Affiliation(s)
- Mara Clapp
- Department of Developmental and Molecular Biology, Albert Einstein College of Medicine of Yeshiva University, Bronx, NY, USA
| | - Florence L Marlow
- Department of Developmental and Molecular Biology, Albert Einstein College of Medicine of Yeshiva University, Bronx, NY, USA.
- Department of Neuroscience, Albert Einstein College of Medicine of Yeshiva University, Bronx, NY, USA.
- Department of Cell, Developmental and Regenerative Medicine, Icahn School of Medicine at Mount Sinai, One Gustave L. Levy Place, Box 1020, New York, NY, 10029-6574, USA.
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28
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Abstract
Localized mRNA translation is a widespread mechanism for targeting protein synthesis, important for cell fate, motility and pathogenesis. In Drosophila, the spatiotemporal control of gurken/TGF-α mRNA translation is required for establishing the embryonic body axes. A number of recent studies have highlighted key aspects of the mechanism of gurken mRNA translational control at the dorsoanterior corner of the mid-stage oocyte. Orb/CPEB and Wispy/GLD-2 are required for polyadenylation of gurken mRNA, but unlocalized gurken mRNA in the oocyte is not fully polyadenylated. 1 At the dorsoanterior corner, Orb and gurken mRNA have been shown to be enriched at the edge of Processing bodies, where translation occurs. 2 Over-expression of Orb in the adjacent nurse cells, where gurken mRNA is transcribed, is sufficient to cause mis-expression of Gurken protein. 3 In orb mutant egg chambers, reducing the activity of CK2, a Serine/Threonine protein kinase, enhances the ventralized phenotype, consistent with perturbation of gurken translation. 4 Here we show that sites phosphorylated by CK2 overlap with active Orb and with Gurken protein expression. Together with our new findings we consolidate the literature into a working model for gurken mRNA translational control and review the role of kinases, cell cycle factors and polyadenylation machinery highlighting a multitude of conserved factors and mechanisms in the Drosophila egg chamber.
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Affiliation(s)
| | - Timothy T Weil
- a Department of Zoology , University of Cambridge , Cambridge , UK
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29
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Trcek T, Lionnet T, Shroff H, Lehmann R. mRNA quantification using single-molecule FISH in Drosophila embryos. Nat Protoc 2016; 12:1326-1348. [PMID: 28594816 DOI: 10.1038/nprot.2017.030] [Citation(s) in RCA: 58] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
Spatial information is critical to the interrogation of developmental and tissue-level regulation of gene expression. However, this information is usually lost when global mRNA levels from tissues are measured using reverse transcriptase PCR, microarray analysis or high-throughput sequencing. By contrast, single-molecule fluorescence in situ hybridization (smFISH) preserves the spatial information of the cellular mRNA content with subcellular resolution within tissues. Here we describe an smFISH protocol that allows for the quantification of single mRNAs in Drosophila embryos, using commercially available smFISH probes (e.g., short fluorescently labeled DNA oligonucleotides) in combination with wide-field epifluorescence, confocal or instant structured illumination microscopy (iSIM, a super-resolution imaging approach) and a spot-detection algorithm. Fixed Drosophila embryos are hybridized in solution with a mixture of smFISH probes, mounted onto coverslips and imaged in 3D. Individual fluorescently labeled mRNAs are then localized within tissues and counted using spot-detection software to generate quantitative, spatially resolved gene expression data sets. With minimum guidance, a graduate student can successfully implement this protocol. The smFISH procedure described here can be completed in 4-5 d.
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Affiliation(s)
- Tatjana Trcek
- Howard Hughes Medical Institute, Skirball Institute of Biomolecular Medicine, Department of Cell Biology, NYU School of Medicine, New York, New York, USA
| | - Timothée Lionnet
- Transcription Imaging Consortium, Janelia Research Campus, Howard Hughes Medical Institute, Ashburn, Virginia, USA
| | - Hari Shroff
- Section on High Resolution Optical Imaging, National Institute of Biomedical Imaging and Bioengineering, National Institutes of Health, Bethesda, Maryland, USA
| | - Ruth Lehmann
- Howard Hughes Medical Institute, Skirball Institute of Biomolecular Medicine, Department of Cell Biology, NYU School of Medicine, New York, New York, USA
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