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Bayer LV, Omar OS, Bratu DP, Catrina IE. PinMol: Python application for designing molecular beacons for live cell imaging of endogenous mRNAs. RNA (NEW YORK, N.Y.) 2019; 25:305-318. [PMID: 30573696 PMCID: PMC6380279 DOI: 10.1261/rna.069542.118] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 11/09/2018] [Accepted: 12/04/2018] [Indexed: 06/09/2023]
Abstract
Molecular beacons are nucleic acid oligomers labeled with a fluorophore and a quencher that fold in a hairpin-shaped structure, which fluoresce only when bound to their target RNA. They are used for the visualization of endogenous mRNAs in live cells. Here, we report a Python program (PinMol) that designs molecular beacons best suited for live cell imaging by using structural information from secondary structures of the target RNA, predicted via energy minimization approaches. PinMol takes into account the accessibility of the targeted regions, as well as the inter- and intramolecular interactions of each selected probe. To demonstrate its applicability, we synthesized an oskar mRNA-specific molecular beacon (osk1236), which is selected by PinMol to target a more accessible region than a manually designed oskar-specific molecular beacon (osk2216). We previously demonstrated osk2216 to be efficient in detecting oskar mRNA in in vivo experiments. Here, we show that osk1236 outperformed osk2216 in live cell imaging experiments.
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Affiliation(s)
- Livia V Bayer
- Biological Sciences Department, Hunter College, City University of New York, New York, New York 10065, USA
- Program in Molecular, Cellular, and Developmental Biology, The Graduate Center, City University of New York, New York, New York 10016, USA
| | - Omar S Omar
- Biological Sciences Department, Hunter College, City University of New York, New York, New York 10065, USA
- Program in Molecular, Cellular, and Developmental Biology, The Graduate Center, City University of New York, New York, New York 10016, USA
| | - Diana P Bratu
- Biological Sciences Department, Hunter College, City University of New York, New York, New York 10065, USA
- Program in Molecular, Cellular, and Developmental Biology, The Graduate Center, City University of New York, New York, New York 10016, USA
| | - Irina E Catrina
- Biological Sciences Department, Hunter College, City University of New York, New York, New York 10065, USA
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2
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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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3
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Real-Hohn A, Provance DW, Gonçalves RB, Denani CB, de Oliveira AC, Salerno VP, Oliveira Gomes AM. Impairing the function of MLCK, myosin Va or myosin Vb disrupts Rhinovirus B14 replication. Sci Rep 2017; 7:17153. [PMID: 29215055 PMCID: PMC5719429 DOI: 10.1038/s41598-017-17501-z] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2017] [Accepted: 11/27/2017] [Indexed: 12/19/2022] Open
Abstract
Together, the three human rhinovirus (RV) species are the most frequent cause of the common cold. Because of their high similarity with other viral species of the genus Enterovirus, within the large family Picornaviridae, studies on RV infectious activities often offer a less pathogenic model for more aggressive enteroviruses, e.g. poliovirus or EV71. Picornaviruses enter via receptor mediated endocytosis and replicate in the cytosol. Most of them depend on functional F-actin, Rab proteins, and probably motor proteins. To assess the latter, we evaluated the role of myosin light chain kinase (MLCK) and two myosin V isoforms (Va and Vb) in RV-B14 infection. We report that ML-9, a very specific MLCK inhibitor, dramatically reduced RV-B14 entry. We also demonstrate that RV-B14 infection in cells expressing dominant-negative forms of myosin Va and Vb was impaired after virus entry. Using immunofluorescent localization and immunoprecipitation, we show that myosin Va co-localized with RV-B14 exclusively after viral entry (15 min post infection) and that myosin Vb was present in the clusters of newly synthesized RNA in infected cells. These clusters, observed at 180 min post infection, are reminiscent of replication sites. Taken together, these results identify myosin light chain kinase, myosin Va and myosin Vb as new players in RV-B14 infection that participate directly or indirectly in different stages of the viral cycle.
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Affiliation(s)
- Antonio Real-Hohn
- Instituto de Bioquímica Médica Leopoldo de Meis, Universidade Federal do Rio de Janeiro, Rio de Janeiro, Brazil.,Departamento de Biociências da Atividade Física, Escola de Educação Física e Desportos, Universidade Federal Rio do Janeiro, Rio de Janeiro, Brazil.,Instituto Nacional de Ciência e Tecnologia de Biologia Estrutural e Bioimagem, Rio de Janeiro, RJ, Brazil
| | - D William Provance
- Center for Technological Development in Health, National Institute of Science and Technology for Innovation in Diseases of Neglected Populations, Oswaldo Cruz Foundation/Fiocruz, Rio de Janeiro, Brazil
| | - Rafael Braga Gonçalves
- Departamento de Bioquímica, Instituto Biomédico, Universidade Federal do Estado do Rio de Janeiro, Rio de Janeiro, Brazil.,Instituto Nacional de Ciência e Tecnologia de Biologia Estrutural e Bioimagem, Rio de Janeiro, RJ, Brazil
| | - Caio Bidueira Denani
- Instituto de Bioquímica Médica Leopoldo de Meis, Universidade Federal do Rio de Janeiro, Rio de Janeiro, Brazil.,Instituto Nacional de Ciência e Tecnologia de Biologia Estrutural e Bioimagem, Rio de Janeiro, RJ, Brazil
| | - Andréa Cheble de Oliveira
- Instituto de Bioquímica Médica Leopoldo de Meis, Universidade Federal do Rio de Janeiro, Rio de Janeiro, Brazil.,Instituto Nacional de Ciência e Tecnologia de Biologia Estrutural e Bioimagem, Rio de Janeiro, RJ, Brazil
| | - Verônica P Salerno
- Departamento de Biociências da Atividade Física, Escola de Educação Física e Desportos, Universidade Federal Rio do Janeiro, Rio de Janeiro, Brazil
| | - Andre Marco Oliveira Gomes
- Instituto de Bioquímica Médica Leopoldo de Meis, Universidade Federal do Rio de Janeiro, Rio de Janeiro, Brazil. .,Instituto Nacional de Ciência e Tecnologia de Biologia Estrutural e Bioimagem, Rio de Janeiro, RJ, Brazil.
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Retrotransposons Mimic Germ Plasm Determinants to Promote Transgenerational Inheritance. Curr Biol 2017; 27:3010-3016.e3. [PMID: 28966088 DOI: 10.1016/j.cub.2017.08.036] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/25/2017] [Revised: 07/14/2017] [Accepted: 08/15/2017] [Indexed: 11/21/2022]
Abstract
Retrotransposons are a pervasive class of mobile elements present in the genomes of virtually all forms of life [1, 2]. In metazoans, these are preferentially active in the germline, which, in turn, mounts defenses that restrain their activity [3, 4]. Here we report that certain classes of retrotransposons ensure transgenerational inheritance by invading presumptive germ cells before they are formed. Using sensitized Drosophila and zebrafish models, we found that diverse classes of retrotransposons migrate to the germ plasm, a specialized region of the oocyte that prefigures germ cells and specifies the germline of descendants in the fertilized egg. In Drosophila, we found evidence for a "stowaway" model, whereby Tahre retroelements traffic to the germ plasm by mimicking oskar RNAs and engaging the Staufen-dependent active transport machinery. Consistent with this, germ plasm determinants attracted retroelement RNAs even when these components were ectopically positioned in bipolar oocytes. Likewise, vertebrate retrotransposons similarly migrated to the germ plasm in zebrafish oocytes. Together, these results suggest that germ plasm targeting represents a fitness strategy adopted by some retrotransposons to ensure transgenerational propagation.
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Catrina IE, Bayer LV, Yanez G, McLaughlin JM, Malaczek K, Bagaeva E, Marras SAE, Bratu DP. The temporally controlled expression of Drongo, the fruit fly homolog of AGFG1, is achieved in female germline cells via P-bodies and its localization requires functional Rab11. RNA Biol 2016; 13:1117-1132. [PMID: 27654348 PMCID: PMC5100350 DOI: 10.1080/15476286.2016.1218592] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2016] [Revised: 07/22/2016] [Accepted: 07/26/2016] [Indexed: 10/21/2022] Open
Abstract
To achieve proper RNA transport and localization, RNA viruses exploit cellular vesicular trafficking pathways. AGFG1, a host protein essential for HIV-1 and Influenza A replication, has been shown to mediate release of intron-containing viral RNAs from the perinuclear region. It is still unknown what its precise role in this release is, or whether AGFG1 also participates in cytoplasmic transport. We report for the first time the expression patterns during oogenesis for Drongo, the fruit fly homolog of AGFG1. We find that temporally controlled Drongo expression is achieved by translational repression of drongo mRNA within P-bodies. Here we show a first link between the recycling endosome pathway and Drongo, and find that proper Drongo localization at the oocyte's cortex during mid-oogenesis requires functional Rab11.
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Affiliation(s)
- Irina E. Catrina
- Biological Sciences Department, Hunter College, City University of New York, New York, NY, USA
| | - Livia V. Bayer
- Biological Sciences Department, Hunter College, City University of New York, New York, NY, USA
- Program in Molecular, Cellular, and Developmental Biology, The Graduate Center, City University of New York, New York, NY, USA
| | - Giussepe Yanez
- Biological Sciences Department, Hunter College, City University of New York, New York, NY, USA
| | - John M. McLaughlin
- Biological Sciences Department, Hunter College, City University of New York, New York, NY, USA
- Program in Molecular, Cellular, and Developmental Biology, The Graduate Center, City University of New York, New York, NY, USA
| | - Kornelia Malaczek
- Biological Sciences Department, Hunter College, City University of New York, New York, NY, USA
| | - Ekaterina Bagaeva
- Biological Sciences Department, Hunter College, City University of New York, New York, NY, USA
| | - Salvatore A. E. Marras
- Department of Microbiology, Biochemistry & Molecular Genetics, Public Health Research Institute, New Jersey Medical School - Rutgers, The State University of New Jersey, Newark, NJ, USA
| | - Diana P. Bratu
- Biological Sciences Department, Hunter College, City University of New York, New York, NY, USA
- Program in Molecular, Cellular, and Developmental Biology, The Graduate Center, City University of New York, New York, NY, USA
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6
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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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Abstract
The Drosophila melanogaster ovary has served as a popular and successful model for understanding a wide range of biological processes: stem cell function, germ cell development, meiosis, cell migration, morphogenesis, cell death, intercellular signaling, mRNA localization, and translational control. This review provides a brief introduction to Drosophila oogenesis, along with a survey of its diverse biological topics and the advanced genetic tools that continue to make this a popular developmental model system.
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Hövelmann F, Gaspar I, Loibl S, Ermilov EA, Röder B, Wengel J, Ephrussi A, Seitz O. Brightness through local constraint--LNA-enhanced FIT hybridization probes for in vivo ribonucleotide particle tracking. Angew Chem Int Ed Engl 2014; 53:11370-5. [PMID: 25167966 DOI: 10.1002/anie.201406022] [Citation(s) in RCA: 49] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2014] [Indexed: 11/11/2022]
Abstract
Imaging the dynamics of RNA in living cells is usually performed by means of transgenic approaches that require modification of RNA targets and cells. Fluorogenic hybridization probes would also allow the analysis of wild-type organisms. We developed nuclease-resistant DNA forced intercalation (FIT) probes that combine the high enhancement of fluorescence upon hybridization with the high brightness required to allow tracking of individual ribonucleotide particles (RNPs). In our design, a single thiazole orange (TO) intercalator dye is linked as a nucleobase surrogate and an adjacent locked nucleic acid (LNA) unit serves to introduce a local constraint. This closes fluorescence decay channels and thereby increases the brightness of the probe-target duplexes. As few as two probes were sufficient to enable the tracking of oskar mRNPs in wild-type living Drosophila melanogaster oocytes.
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Affiliation(s)
- Felix Hövelmann
- Department of Chemistry, Humboldt-Universität zu Berlin, Brook-Taylor-Strasse 2, 12489 Berlin (Germany)
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Hövelmann F, Gaspar I, Loibl S, Ermilov EA, Röder B, Wengel J, Ephrussi A, Seitz O. Helligkeit durch lokale Rigidifizierung - LNA-verstärkte FIT-Sonden zur bildgebenden Darstellung von Ribonukleotidpartikeln in vivo. Angew Chem Int Ed Engl 2014. [DOI: 10.1002/ange.201406022] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
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10
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Heraud-Farlow JE, Kiebler MA. The multifunctional Staufen proteins: conserved roles from neurogenesis to synaptic plasticity. Trends Neurosci 2014; 37:470-9. [PMID: 25012293 PMCID: PMC4156307 DOI: 10.1016/j.tins.2014.05.009] [Citation(s) in RCA: 75] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2014] [Revised: 05/22/2014] [Accepted: 05/27/2014] [Indexed: 12/11/2022]
Abstract
Staufen (Stau) proteins have evolutionarily conserved functions in the brain. Stau proteins asymmetrically segregate mRNAs during mouse and fly neurogenesis. Stau proteins regulate synaptic plasticity and memory formation in flies and mammals. Stau proteins have roles in translation, localisation, and ribonucleoprotein formation. New data indicate that mammalian Stau1 and Stau2 can both stabilise and destabilise target mRNAs.
Staufen (Stau) proteins belong to a family of RNA-binding proteins (RBPs) that are important for RNA localisation in many organisms. In this review we discuss recent findings on the conserved role played by Stau during both the early differentiation of neurons and in the synaptic plasticity of mature neurons. Recent molecular data suggest mechanisms for how Stau2 regulates mRNA localisation, mRNA stability, translation, and ribonucleoprotein (RNP) assembly. We offer a perspective on how this multifunctional RBP has been adopted to regulate mRNA localisation under several different cellular and developmental conditions.
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Affiliation(s)
- Jacki E Heraud-Farlow
- Department of Chromosome Biology, Max F. Perutz Laboratories, University of Vienna, 1030 Vienna, Austria
| | - Michael A Kiebler
- Department of Anatomy and Cell Biology, Ludwig-Maximilians-University, 80336 Munich, Germany.
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11
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The functions and regulatory principles of mRNA intracellular trafficking. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2014; 825:57-96. [PMID: 25201103 DOI: 10.1007/978-1-4939-1221-6_2] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/11/2023]
Abstract
The subcellular localization of RNA molecules is a key step in the control of gene expression that impacts a broad array of biological processes in different organisms and cell types. Like other aspects of posttranscriptional gene regulation discussed in this collection of reviews, the intracellular trafficking of mRNAs is modulated by a complex regulatory code implicating specific cis-regulatory elements, RNA-binding proteins, and cofactors that function combinatorially to dictate precise localization mechanisms. In this review, we first discuss the functional benefits of transcript localization, the regulatory principles involved, and specific molecular mechanisms that have been described for a few well-characterized mRNAs. We also overview some of the emerging genomic and imaging technologies that have provided significant insights into this layer of gene regulation. Finally, we highlight examples of human diseases where defective transcript localization has been documented.
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Lasko P. mRNA localization and translational control in Drosophila oogenesis. Cold Spring Harb Perspect Biol 2012; 4:cshperspect.a012294. [PMID: 22865893 DOI: 10.1101/cshperspect.a012294] [Citation(s) in RCA: 87] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Abstract
Localization of an mRNA species to a particular subcellular region can complement translational control mechanisms to produce a restricted spatial distribution of the protein it encodes. mRNA localization has been studied most in asymmetric cells such as budding yeast, early embryos, and neurons, but the process is likely to be more widespread. This article reviews the current state of knowledge about the mechanisms of mRNA localization and its functions in early embryonic development, focusing on Drosophila where the relevant knowledge is most advanced. Links between mRNA localization and translational control mechanisms also are examined.
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Affiliation(s)
- Paul Lasko
- Department of Biology, Bellini Life Sciences Building, McGill University, Montréal, Québec H3G 0B1, Canada.
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13
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Catrina IE, Marras SAE, Bratu DP. Tiny molecular beacons: LNA/2'-O-methyl RNA chimeric probes for imaging dynamic mRNA processes in living cells. ACS Chem Biol 2012; 7:1586-95. [PMID: 22738327 DOI: 10.1021/cb300178a] [Citation(s) in RCA: 41] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
Abstract
New approaches for imaging dynamic processes involving RNAs in living cells are continuously being developed and optimized. The use of molecular beacons synthesized from 2'-O-methylribonucleotides (which are resistant to cellular nucleases) is an established approach for visualizing native mRNAs in real time. In order to spatially and temporally resolve dynamic steps involving RNA in cells, molecular beacons need to efficiently hybridize to their RNA targets. To expand the repertoire of target sites accessible to molecular beacons, we decreased the length of their probe sequences and altered their backbone by the inclusion of LNA (locked nucleic acid) nucleotides. We named these new LNA/2'-O-methyl RNA chimera oligonucleotides "tiny molecular beacons". We analyzed these tiny molecular beacons and found that the incorporation of just a few LNA nucleotides enables these shorter probes to stably anneal to more structured regions of the RNA than is possible with conventional molecular beacons. The ease of synthesis of tiny molecular beacons and the flexibility to couple them to a large variety of fluorophores and quenchers render them optimal for the detection of less abundant and/or highly structured RNAs. To determine their efficiency to detect endogenous mRNAs in live specimens, we designed tiny molecular beacons that were specific for oskar mRNA and microinjected them into living Drosophila melanogaster oocytes. We then imaged the live oocytes via spinning disk confocal microscopy. The results demonstrate that tiny molecular beacons hybridize to target mRNA at faster rates than classically designed molecular beacons and are able to access previously inaccessible target regions.
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Affiliation(s)
- Irina E. Catrina
- Biological Sciences Department,
Hunter College, City University of New York, New York, New York 10065, United States
| | - Salvatore A. E. Marras
- Public Health Research Institute,
Department of Microbiology and Molecular Genetics, University of Medicine and Dentistry of New Jersey, Newark, New
Jersey 07103, United States
| | - Diana P. Bratu
- Biological Sciences Department,
Hunter College, City University of New York, New York, New York 10065, United States
- Program in Molecular, Cellular,
and Developmental Biology, and Program in Biochemistry, The Graduate
Center, City University of New York, New
York, New York 10016, United States
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14
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Jansen RP, Niessing D. Assembly of mRNA-protein complexes for directional mRNA transport in eukaryotes--an overview. Curr Protein Pept Sci 2012; 13:284-93. [PMID: 22708485 PMCID: PMC3474952 DOI: 10.2174/138920312801619493] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2011] [Revised: 01/10/2012] [Accepted: 01/20/2012] [Indexed: 12/11/2022]
Abstract
At all steps from transcription to translation, RNA-binding proteins play important roles in determining mRNA function. Initially it was believed that for the vast majority of transcripts the role of RNA-binding proteins is limited to general functions such as splicing and translation. However, work from recent years showed that members of this class of proteins also recognize several mRNAs via cis-acting elements for their incorporation into large motor-containing particles. These particles are transported to distant subcellular sites, where they become subsequently translated. This process, called mRNA localization, occurs along microtubules or actin filaments, and involves kinesins, dyneins, as well as myosins. Although mRNA localization has been detected in a large number of organisms from fungi to humans, the underlying molecular machineries are not well understood. In this review we will outline general principles of mRNA localization and highlight three examples, for which a comparably large body of information is available. The first example is She2p/She3p-dependent localization of ASH1 mRNA in budding yeast. It is particularly well suited to highlight the interdependence between different steps of mRNA localization. The second example is Staufen-dependent localization of oskar mRNA in the Drosophila embryo, for which the importance of nuclear events for cytoplasmic localization and translational control has been clearly demonstrated. The third example summarizes Egalitarian/Bicaudal D-dependent mRNA transport events in the oocyte and embryo of Drosophila. We will highlight general themes and differences, point to similarities in other model systems, and raise open questions that might be answered in the coming years.
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Affiliation(s)
- Ralf-Peter Jansen
- Interfaculty Institute for Biochemistry, University of Tübingen, Tübingen, Germany
| | - Dierk Niessing
- Institute of Structural Biology, Helmholtz Zentrum München–German Research Center for Environmental Health, München, Germany
- Gene Center and Department of Biochemistry, Ludwig-Maximilians-University, München, Germany
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15
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Amrute-Nayak M, Bullock SL. Single-molecule assays reveal that RNA localization signals regulate dynein-dynactin copy number on individual transcript cargoes. Nat Cell Biol 2012; 14:416-23. [PMID: 22366687 PMCID: PMC3343632 DOI: 10.1038/ncb2446] [Citation(s) in RCA: 63] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/07/2011] [Accepted: 01/24/2012] [Indexed: 11/13/2022]
Abstract
Subcellular localization of mRNAs by cytoskeletal motors plays critical roles in the spatial control of protein function1. However, optical limitations of studying mRNA transport in vivo mean that there is little mechanistic insight into how transcripts are packaged and linked to motors, and how the movement of mRNA:motor complexes on the cytoskeleton is orchestrated. Here, we have reconstituted transport of mRNPs containing specific RNAs in vitro. We show directly that mRNAs that are either apically localized or non-localized in Drosophila embryos associate with the dynein motor and move bidirectionally on individual microtubules, with localizing mRNPs exhibiting a strong minus-end-directed bias. Single-molecule fluorescence measurements reveal that RNA localization signals increase the average number of dynein and dynactin components recruited to individual mRNPs. We find that, surprisingly, individual RNA molecules are present in motile mRNPs in vitro and present evidence that this is also the case in vivo. Thus, RNA oligomerization is not obligatory for transport. Our findings lead to a model in which RNA localization signals produce highly polarized distributions of transcript populations through modest changes in motor copy number on single mRNA molecules.
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Affiliation(s)
- Mamta Amrute-Nayak
- Cell Biology Division, MRC Laboratory of Molecular Biology, Hills Road, Cambridge CB2 0QH, UK
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16
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van de Giessen M, van der Laan A, Hendriks EA, Vidorreta M, Reiber JHC, Jost CR, Tanke HJ, Lelieveldt BPF. Fully automated attenuation measurement and motion correction in FLIP image sequences. IEEE TRANSACTIONS ON MEDICAL IMAGING 2012; 31:461-473. [PMID: 21997250 DOI: 10.1109/tmi.2011.2171497] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
Fluorescence loss in photobleaching (FLIP) is a method to study compartment connectivity in living cells. A FLIP sequence is obtained by alternatively bleaching a spot in a cell and acquiring an image of the complete cell. Connectivity is estimated by comparing fluorescence signal attenuation in different cell parts. The measurements of the fluorescence attenuation are hampered by the low signal to noise ratio of the FLIP sequences, by sudden sample shifts and by sample drift. This paper describes a method that estimates the attenuation by modeling photobleaching as exponentially decaying signals. Sudden motion artifacts are minimized by registering the frames of a FLIP sequence to target frames based on the estimated model and by removing frames that contain deformations. Linear motion (sample drift) is reduced by minimizing the entropy of the estimated attenuation coefficients. Experiments on 16 in vivo FLIP sequences of muscle cells in Drosophila show that the proposed method results in fluorescence attenuations similar to the manually identified gold standard, but with standard deviations of approximately 50 times smaller. As a result of this higher precision, cell compartment edges and details such as cell nuclei become clearly discernible. The main value of this method is that it uses a model of the bleaching process to correct motion and that the model based fluorescence intensity and attenuation estimates can be interpreted easily. The proposed method is fully automatic, and runs in approximately one minute per sequence, making it suitable for unsupervised batch processing of large data series.
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Affiliation(s)
- Martijn van de Giessen
- Division of Image Processing (LKEB), Leiden University Medical Center, 2300 RC Leiden, The Netherlands.
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Gagnon JA, Mowry KL. Molecular motors: directing traffic during RNA localization. Crit Rev Biochem Mol Biol 2011; 46:229-39. [PMID: 21476929 DOI: 10.3109/10409238.2011.572861] [Citation(s) in RCA: 52] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
RNA localization, the enrichment of RNA in a specific subcellular region, is a mechanism for the establishment and maintenance of cellular polarity in a variety of systems. Ultimately, this results in a universal method for spatially restricting gene expression. Although the consequences of RNA localization are well-appreciated, many of the mechanisms that are responsible for carrying out polarized transport remain elusive. Several recent studies have illuminated the roles that molecular motor proteins play in the process of RNA localization. These studies have revealed complex mechanisms in which the coordinated action of one or more motor proteins can act at different points in the localization process to direct RNAs to their final destination. In this review, we discuss recent findings from several different systems in an effort to clarify pathways and mechanisms that control the directed movement of RNA.
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Affiliation(s)
- James A Gagnon
- Department of Molecular Biology, Cell Biology & Biochemistry, Brown University, Providence, RI, USA
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18
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Mikl M, Vendra G, Doyle M, Kiebler MA. RNA localization in neurite morphogenesis and synaptic regulation: current evidence and novel approaches. J Comp Physiol A Neuroethol Sens Neural Behav Physiol 2010; 196:321-34. [PMID: 20237785 PMCID: PMC2858279 DOI: 10.1007/s00359-010-0520-x] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2009] [Revised: 03/04/2010] [Accepted: 03/04/2010] [Indexed: 12/23/2022]
Abstract
It is now generally accepted that RNA localization in the central nervous system conveys important roles both during development and in the adult brain. Of special interest is protein synthesis located at the synapse, as this potentially confers selective synaptic modification and has been implicated in the establishment of memories. However, the underlying molecular events are largely unknown. In this review, we will first discuss novel findings that highlight the role of RNA localization in neurons. We will focus on the role of RNA localization in neurotrophin signaling, axon outgrowth, dendrite and dendritic spine morphogenesis as well as in synaptic plasticity. Second, we will briefly present recent work on the role of microRNAs in translational control in dendrites and its implications for learning and memory. Finally, we discuss recent approaches to visualize RNAs in living cells and their employment for studying RNA trafficking in neurons.
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Affiliation(s)
- Martin Mikl
- Center for Brain Research, Medical University of Vienna, Austria
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19
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Abstract
Understanding subcellular dynamic processes governing pathogenic mechanisms is a necessary step towards the development of new drugs and strategies against infectious diseases. Subcellular pathogenic mechanisms, such as viral invasion processes involve highly dynamic nanometric-scale objects and rapid molecular interactions that require the study of individual particle paths. Single-particle tracking methods allow visualizing and characterizing the dynamics of biological objects, and provide a straightforward and accurate means to understand subcellular processes. This review describes a number of particle-tracking methods in time-lapse microscopy sequences and provides examples of using such techniques to investigate mechanisms of host-pathogen interactions.
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Affiliation(s)
- Nicolas Chenouard
- Institut Pasteur, Unité d'Analyse d'Images Quantitative, CNRS URA 2582, Paris, France
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