151
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Saroufim MA, Bensidoun P, Raymond P, Rahman S, Krause MR, Oeffinger M, Zenklusen D. The nuclear basket mediates perinuclear mRNA scanning in budding yeast. J Cell Biol 2016; 211:1131-40. [PMID: 26694838 PMCID: PMC4687876 DOI: 10.1083/jcb.201503070] [Citation(s) in RCA: 50] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Single-molecule resolution particle tracking reveals that mRNAs in S. cerevisiae scan the nuclear periphery before being exported to the cytoplasm and that this process is mediated by both components of the nuclear basket and the mRNP. After synthesis and transit through the nucleus, messenger RNAs (mRNAs) are exported to the cytoplasm through the nuclear pore complex (NPC). At the NPC, messenger ribonucleoproteins (mRNPs) first encounter the nuclear basket where mRNP rearrangements are thought to allow access to the transport channel. Here, we use single mRNA resolution live cell microscopy and subdiffraction particle tracking to follow individual mRNAs on their path toward the cytoplasm. We show that when reaching the nuclear periphery, RNAs are not immediately exported but scan along the nuclear periphery, likely to find a nuclear pore allowing export. Deletion or mutation of the nuclear basket proteins MLP1/2 or the mRNA binding protein Nab2 changes the scanning behavior of mRNPs at the nuclear periphery, shortens residency time at nuclear pores, and results in frequent release of mRNAs back into the nucleoplasm. These observations suggest a role for the nuclear basket in providing an interaction platform that keeps RNAs at the periphery, possibly to allow mRNP rearrangements before export.
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Affiliation(s)
- Mark-Albert Saroufim
- Departement de Biochimie et Medecine Moleculaire, Faculte de Medecine, Universite de Montreal, H3T 1J4 Montreal, Quebec, Canada
| | - Pierre Bensidoun
- Departement de Biochimie et Medecine Moleculaire, Faculte de Medecine, Universite de Montreal, H3T 1J4 Montreal, Quebec, Canada Institut de Recherches Cliniques de Montreal, H2W 1R7 Montreal, Quebec, Canada
| | - Pascal Raymond
- Departement de Biochimie et Medecine Moleculaire, Faculte de Medecine, Universite de Montreal, H3T 1J4 Montreal, Quebec, Canada
| | - Samir Rahman
- Departement de Biochimie et Medecine Moleculaire, Faculte de Medecine, Universite de Montreal, H3T 1J4 Montreal, Quebec, Canada
| | - Matthew R Krause
- Montreal Neurological Institute, McGill University, H3A 2B4 Montreal, Quebec, Canada
| | - Marlene Oeffinger
- Departement de Biochimie et Medecine Moleculaire, Faculte de Medecine, Universite de Montreal, H3T 1J4 Montreal, Quebec, Canada Institut de Recherches Cliniques de Montreal, H2W 1R7 Montreal, Quebec, Canada Faculty of Medicine, Division of Experimental Medicine, McGill University, H3A 2B4 Montreal, Quebec, Canada
| | - Daniel Zenklusen
- Departement de Biochimie et Medecine Moleculaire, Faculte de Medecine, Universite de Montreal, H3T 1J4 Montreal, Quebec, Canada
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152
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Haimovich G, Zabezhinsky D, Haas B, Slobodin B, Purushothaman P, Fan L, Levin JZ, Nusbaum C, Gerst JE. Use of the MS2 aptamer and coat protein for RNA localization in yeast: A response to "MS2 coat proteins bound to yeast mRNAs block 5' to 3' degradation and trap mRNA decay products: implications for the localization of mRNAs by MS2-MCP system". RNA (NEW YORK, N.Y.) 2016; 22:660-6. [PMID: 26968626 PMCID: PMC4836641 DOI: 10.1261/rna.055095.115] [Citation(s) in RCA: 44] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/29/2015] [Accepted: 02/09/2016] [Indexed: 05/17/2023]
Abstract
The MS2 system has been extensively used to visualize single mRNA molecules in live cells and follow their localization and behavior. In their Letter to the Editor recently published, Garcia and Parker suggest that use of the MS2 system may yield erroneous mRNA localization results due to the accumulation of 3' decay products. Here we cite published works and provide new data which demonstrate that this is not a phenomenon general to endogenously expressed MS2-tagged transcripts, and that some of the results obtained in their study could have arisen from artifacts of gene expression.
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Affiliation(s)
- Gal Haimovich
- Department of Molecular Genetics, Weizmann Institute of Science, Rehovot 7610001, Israel
| | - Dmitry Zabezhinsky
- Department of Molecular Genetics, Weizmann Institute of Science, Rehovot 7610001, Israel
| | - Brian Haas
- Broad Institute of MIT and Harvard, Cambridge, Massachusetts 02142, USA
| | - Boris Slobodin
- Department of Molecular Genetics, Weizmann Institute of Science, Rehovot 7610001, Israel
| | | | - Lin Fan
- Broad Institute of MIT and Harvard, Cambridge, Massachusetts 02142, USA
| | - Joshua Z Levin
- Broad Institute of MIT and Harvard, Cambridge, Massachusetts 02142, USA
| | - Chad Nusbaum
- Broad Institute of MIT and Harvard, Cambridge, Massachusetts 02142, USA
| | - Jeffrey E Gerst
- Department of Molecular Genetics, Weizmann Institute of Science, Rehovot 7610001, Israel
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153
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Halstead JM, Wilbertz JH, Wippich F, Lionnet T, Ephrussi A, Chao JA. TRICK: A Single-Molecule Method for Imaging the First Round of Translation in Living Cells and Animals. Methods Enzymol 2016; 572:123-57. [PMID: 27241753 DOI: 10.1016/bs.mie.2016.02.027] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/08/2022]
Abstract
The life of an mRNA is dynamic within a cell. The development of quantitative fluorescent microscopy techniques to image single molecules of RNA has allowed many aspects of the mRNA lifecycle to be directly observed in living cells. Recent advances in live-cell multicolor RNA imaging, however, have now made it possible to investigate RNA metabolism in greater detail. In this chapter, we present an overview of the design and implementation of the translating RNA imaging by coat protein knockoff RNA biosensor, which allows untranslated mRNAs to be distinguished from ones that have undergone a round of translation. The methods required for establishing this system in mammalian cell lines and Drosophila melanogaster oocytes are described here, but the principles may be applied to any experimental system.
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Affiliation(s)
- J M Halstead
- Friedrich Miescher Institute for Biomedical Research, Basel, Switzerland
| | - J H Wilbertz
- Friedrich Miescher Institute for Biomedical Research, Basel, Switzerland; University of Basel, Basel, Switzerland
| | - F Wippich
- European Molecular Biology Laboratory, Heidelberg, Germany
| | - T Lionnet
- Transcription Imaging Consortium, HHMI Janelia Research Campus, Ashburn, VA, United States
| | - A Ephrussi
- European Molecular Biology Laboratory, Heidelberg, Germany
| | - J A Chao
- Friedrich Miescher Institute for Biomedical Research, Basel, Switzerland.
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154
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Abstract
The transcription cycle can be roughly divided into three stages: initiation, elongation, and termination. Understanding the molecular events that regulate all these stages requires a dynamic view of the underlying processes. The development of techniques to visualize and quantify transcription in single living cells has been essential in revealing the transcription kinetics. They have revealed that (a) transcription is heterogeneous between cells and (b) transcription can be discontinuous within a cell. In this review, we discuss the progress in our quantitative understanding of transcription dynamics in living cells, focusing on all parts of the transcription cycle. We present the techniques allowing for single-cell transcription measurements, review evidence from different organisms, and discuss how these experiments have broadened our mechanistic understanding of transcription regulation.
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Affiliation(s)
- Tineke L Lenstra
- Laboratory of Receptor Biology and Gene Expression, Center for Cancer Research, National Cancer Institute, Bethesda, Maryland 20892;
| | - Joseph Rodriguez
- Laboratory of Receptor Biology and Gene Expression, Center for Cancer Research, National Cancer Institute, Bethesda, Maryland 20892;
| | - Huimin Chen
- Laboratory of Receptor Biology and Gene Expression, Center for Cancer Research, National Cancer Institute, Bethesda, Maryland 20892;
| | - Daniel R Larson
- Laboratory of Receptor Biology and Gene Expression, Center for Cancer Research, National Cancer Institute, Bethesda, Maryland 20892;
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155
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Ray J, Shin I, Ilgu M, Bendickson L, Gupta V, Kraus GA, Nilsen-Hamilton M. IMAGEtags: Quantifying mRNA Transcription in Real Time with Multiaptamer Reporters. Methods Enzymol 2016; 572:193-213. [PMID: 27241755 DOI: 10.1016/bs.mie.2016.02.028] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
Cell communications are essential to the organization, development, and maintenance of multicellular organisms. Much of this communication involves changes in RNA transcription and is dynamic. Most methods for studying transcription require interrupting the continuity of cellular function by sacrificing the communicating cells and capturing gene expression information by periodic sampling of individual cells or the population. The IMAGEtag technology to quantify RNA levels in living cells, demonstrated here in yeast, allows individual cells to be tracked over time as they respond to different environmental cues. IMAGEtags are short RNAs consisting of strings of a variable number of tandem aptamers that bind small-molecule ligands. The aptamer strings can vary in length and in configuration of aptamer constituents, such as to contain multiples of the same aptamer or two or more different aptamers that alternate in their occurrence. A minimum effective length is about five aptamers. The maximum length is undefined. The small-molecule ligands are enabled for imaging as fluorophore conjugates. For each IMAGEtag, two fluorophore conjugates are provided, which are FRET pairs. When a cell expresses an RNA containing an IMAGEtag sequence, the aptamers bind their ligands and bring the fluorophores into sufficiently close proximity to allow FRET. The background fluorescence of both fluorophores is minimal in the FRET channel. These features endow IMAGEtags with the sensitivity to report on mRNA expression levels in living cells.
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Affiliation(s)
- J Ray
- Cornell University, Ithaca, NY, United States.
| | - I Shin
- National Forensic Service, Seoul, South Korea
| | - M Ilgu
- Aptalogic Inc., Ames, IA, United States
| | - L Bendickson
- Ames Laboratory, US DOE, Ames, IA, United States; Iowa State University, Ames, IA, United States
| | - V Gupta
- The Scripps Research Institute, Jupiter, FL, United States
| | - G A Kraus
- Ames Laboratory, US DOE, Ames, IA, United States; Iowa State University, Ames, IA, United States
| | - M Nilsen-Hamilton
- Ames Laboratory, US DOE, Ames, IA, United States; Iowa State University, Ames, IA, United States; Aptalogic Inc., Ames, IA, United States.
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156
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Lampasona AA, Czaplinski K. RNA voyeurism: A coming of age story. Methods 2016; 98:10-17. [DOI: 10.1016/j.ymeth.2015.11.024] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/07/2015] [Revised: 11/24/2015] [Accepted: 11/26/2015] [Indexed: 10/22/2022] Open
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157
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Regulation of cell-to-cell variability in divergent gene expression. Nat Commun 2016; 7:11099. [PMID: 27010670 PMCID: PMC4820839 DOI: 10.1038/ncomms11099] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2015] [Accepted: 02/21/2016] [Indexed: 12/03/2022] Open
Abstract
Cell-to-cell variability (noise) is an important feature of gene expression that impacts cell fitness and development. The regulatory mechanism of this variability is not fully understood. Here we investigate the effect on gene expression noise in divergent gene pairs (DGPs). We generated reporters driven by divergent promoters, rearranged their gene order, and probed their expressions using time-lapse fluorescence microscopy and single-molecule fluorescence in situ hybridization (smFISH). We show that two genes in a co-regulated DGP have higher expression covariance compared with the separate, tandem and convergent configurations, and this higher covariance is caused by more synchronized firing of the divergent transcriptions. For differentially regulated DGPs, the regulatory signal of one gene can stochastically ‘leak' to the other, causing increased gene expression noise. We propose that the DGPs' function in limiting or promoting gene expression noise may enhance or compromise cell fitness, providing an explanation for the conservation pattern of DGPs. Gene expression noise affects cell fitness and development. Here, Yan et al. show that co-regulated divergent gene pairs (DGPs) suppress uncorrelated gene expression noise due to more synchronized transcription firing, and differentially regulated DGPs enhance gene expression noise due to transcription leakage.
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158
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Kellermann SJ, Rentmeister A. A Genetically Encodable System for Sequence-Specific Detection of RNAs in Two Colors. Chembiochem 2016; 17:895-9. [PMID: 26919688 DOI: 10.1002/cbic.201500705] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/31/2015] [Indexed: 12/28/2022]
Abstract
Multicolor readout is an important feature of RNA detection techniques aiming at the investigation of RNA localization. Several detection methods have been developed, however they require either transfection of cells with the probe or prior tagging of the target RNA. We report a fully genetically encodable system for simultaneous detection of two RNAs by using green and yellow fluorescence based on tetramolecular fluorescence complementation (TetFC). To obtain yellow fluorescent protein (YFP), substitution T203Y was introduced into one of the three non-fluorescent GFP fragments; this was fused to different variants of the Homo sapiens Pumilio homology domain. Using different sets of fusion proteins we were able to discriminate between two closely related target RNAs based on the fluorescence signals at the respective wavelengths.
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Affiliation(s)
- Stefanie J Kellermann
- Department of Chemistry and Pharmacy, Institute of Biochemistry, University of Münster, Wilhelm-Klemm-Strasse 2, 48149, Münster, Germany.,Department of Chemistry, Institute for Biochemistry and Molecular Biology, University of Hamburg, Martin-Luther-King-Platz 6, 20146, Hamburg, Germany
| | - Andrea Rentmeister
- Department of Chemistry and Pharmacy, Institute of Biochemistry, University of Münster, Wilhelm-Klemm-Strasse 2, 48149, Münster, Germany. .,Cells-in-Motion Cluster of Excellence (EXC 1003-CiM), University of Münster, Wilhelm-Klemm-Strasse 2, 48149, Münster, Germany.
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159
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Musser SM, Grünwald D. Deciphering the Structure and Function of Nuclear Pores Using Single-Molecule Fluorescence Approaches. J Mol Biol 2016; 428:2091-119. [PMID: 26944195 DOI: 10.1016/j.jmb.2016.02.023] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2015] [Revised: 01/05/2016] [Accepted: 02/17/2016] [Indexed: 01/06/2023]
Abstract
Due to its central role in macromolecular trafficking and nucleocytoplasmic information transfer, the nuclear pore complex (NPC) has been studied in great detail using a wide spectrum of methods. Consequently, many aspects of its architecture, general function, and role in the life cycle of a cell are well understood. Over the last decade, fluorescence microscopy methods have enabled the real-time visualization of single molecules interacting with and transiting through the NPC, allowing novel questions to be examined with nanometer precision. While initial single-molecule studies focused primarily on import pathways using permeabilized cells, it has recently proven feasible to investigate the export of mRNAs in living cells. Single-molecule assays can address questions that are difficult or impossible to answer by other means, yet the complexity of nucleocytoplasmic transport requires that interpretation be based on a firm genetic, biochemical, and structural foundation. Moreover, conceptually simple single-molecule experiments remain technically challenging, particularly with regard to signal intensity, signal-to-noise ratio, and the analysis of noise, stochasticity, and precision. We discuss nuclear transport issues recently addressed by single-molecule microscopy, evaluate the limits of existing assays and data, and identify open questions for future studies. We expect that single-molecule fluorescence approaches will continue to be applied to outstanding nucleocytoplasmic transport questions, and that the approaches developed for NPC studies are extendable to additional complex systems and pathways within cells.
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Affiliation(s)
- Siegfried M Musser
- Department of Molecular and Cellular Medicine, College of Medicine, The Texas A&M Health Science Center, 1114 TAMU, College Station, TX 77843, USA.
| | - David Grünwald
- RNA Therapeutics Institute, University of Massachusetts Medical School, Worcester, MA 01605, USA.
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160
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Bensidoun P, Raymond P, Oeffinger M, Zenklusen D. Imaging single mRNAs to study dynamics of mRNA export in the yeast Saccharomyces cerevisiae. Methods 2016; 98:104-114. [PMID: 26784711 DOI: 10.1016/j.ymeth.2016.01.006] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/24/2015] [Revised: 01/12/2016] [Accepted: 01/14/2016] [Indexed: 01/08/2023] Open
Abstract
Regulation of mRNA and protein expression occurs at many levels, initiated at transcription and followed by mRNA processing, export, localization, translation and mRNA degradation. The ability to study mRNAs in living cells has become a critical tool to study and analyze how the various steps of the gene expression pathway are carried out. Here we describe a detailed protocol for real time fluorescent RNA imaging using the PP7 bacteriophage coat protein, which allows mRNA detection with high spatial and temporal resolution in the yeast Saccharomyces cerevisiae, and can be applied to study various stages of mRNA metabolism. We describe the different parameters required for quantitative single molecule imaging in yeast, including strategies for genomic integration, expression of a PP7 coat protein GFP fusion protein, microscope setup and analysis strategies. We illustrate the method's use by analyzing the behavior of nuclear mRNA in yeast and the role of the nuclear basket in mRNA export.
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Affiliation(s)
- Pierre Bensidoun
- Département de Biochimieet médecine moléculaire, Faculté de médecine, Université de Montréal, Montréal, Québec H3C 3J7, Canada; Institut de recherches cliniques de Montréal, 110 Avenue des Pins Ouest, Montréal, Québec H2W 1R7, Canada
| | - Pascal Raymond
- Département de Biochimieet médecine moléculaire, Faculté de médecine, Université de Montréal, Montréal, Québec H3C 3J7, Canada
| | - Marlene Oeffinger
- Département de Biochimieet médecine moléculaire, Faculté de médecine, Université de Montréal, Montréal, Québec H3C 3J7, Canada; Institut de recherches cliniques de Montréal, 110 Avenue des Pins Ouest, Montréal, Québec H2W 1R7, Canada; Faculty of Medicine, Division of Experimental Medicine, McGill University, Montréal, Québec H3A 1A3, Canada
| | - Daniel Zenklusen
- Département de Biochimieet médecine moléculaire, Faculté de médecine, Université de Montréal, Montréal, Québec H3C 3J7, Canada.
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161
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Katz ZB, English BP, Lionnet T, Yoon YJ, Monnier N, Ovryn B, Bathe M, Singer RH. Mapping translation 'hot-spots' in live cells by tracking single molecules of mRNA and ribosomes. eLife 2016; 5. [PMID: 26760529 PMCID: PMC4764586 DOI: 10.7554/elife.10415] [Citation(s) in RCA: 95] [Impact Index Per Article: 11.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2015] [Accepted: 12/29/2015] [Indexed: 11/13/2022] Open
Abstract
Messenger RNA localization is important for cell motility by local protein translation. However, while single mRNAs can be imaged and their movements tracked in single cells, it has not yet been possible to determine whether these mRNAs are actively translating. Therefore, we imaged single β-actin mRNAs tagged with MS2 stem loops colocalizing with labeled ribosomes to determine when polysomes formed. A dataset of tracking information consisting of thousands of trajectories per cell demonstrated that mRNAs co-moving with ribosomes have significantly different diffusion properties from non-translating mRNAs that were exposed to translation inhibitors. These data indicate that ribosome load changes mRNA movement and therefore highly translating mRNAs move slower. Importantly, β-actin mRNA near focal adhesions exhibited sub-diffusive corralled movement characteristic of increased translation. This method can identify where ribosomes become engaged for local protein production and how spatial regulation of mRNA-protein interactions mediates cell directionality.
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Affiliation(s)
- Zachary B Katz
- Department of Anatomy and Structural Biology, Albert Einstein College of Medicine, New York, United States.,Salk Institute for Biological Studies, La Jolla, United States
| | - Brian P English
- Department of Anatomy and Structural Biology, Albert Einstein College of Medicine, New York, United States.,Janelia Research Campus, Howard Hughes Medical Institute, Ashburn, United States
| | - Timothée Lionnet
- Janelia Research Campus, Howard Hughes Medical Institute, Ashburn, United States
| | - Young J Yoon
- Department of Anatomy and Structural Biology, Albert Einstein College of Medicine, New York, United States
| | - Nilah Monnier
- Department of Biological Engineering, Massachusetts Institute of Technology, Cambridge, United States
| | - Ben Ovryn
- Department of Anatomy and Structural Biology, Albert Einstein College of Medicine, New York, United States
| | - Mark Bathe
- Department of Biological Engineering, Massachusetts Institute of Technology, Cambridge, United States
| | - Robert H Singer
- Department of Anatomy and Structural Biology, Albert Einstein College of Medicine, New York, United States.,Janelia Research Campus, Howard Hughes Medical Institute, Ashburn, United States
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162
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Abstract
RNAs have highly complex and dynamic cellular localization patterns. Technologies for imaging RNA in living cells are important for uncovering their function and regulatory pathways. One approach for imaging RNA involves genetically encoding fluorescent RNAs using RNA mimics of green fluorescent protein (GFP). These mimics are RNA aptamers that bind fluorophores resembling those naturally found in GFP and activate their fluorescence. These RNA-fluorophore complexes, including Spinach, Spinach2, and Broccoli, can be used to tag RNAs and to image their localization in living cells. In this article, we describe the generation and optimization of these aptamers, along with strategies for expanding the spectral properties of their associated RNA-fluorophore complexes. We also discuss the structural basis for the fluorescence and photophysical properties of Spinach, and we describe future prospects for designing enhanced RNA-fluorophore complexes with enhanced photostability and increased sensitivity.
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Affiliation(s)
- Mingxu You
- Department of Pharmacology, Weill Medical College, Cornell University, New York, New York 10065; ,
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163
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Abstract
Visualization of single RNA molecules in living cells has enabled the study of synthesis, movement, and localization of mRNAs and has provided insight into gene regulation with sub-second temporal resolution and nanometer spatial resolution. Following transcription in single cells indicates that gene activity is heterogeneous between cells and also exhibits random variability over time even within single cells. Studies of mRNAs in yeast can take advantage of the powerful genetics available in this model organism and allow mechanistic questions to be addressed. In this chapter, we describe an approach for visualizing mRNA and transcription in live yeast cells. The method is based on binding of fluorescently labeled MS2 and PP7 coat proteins to stem loops sequences that are introduced into the gene of interest. We give detailed protocols for the construction of the necessary yeast strains, for image acquisition, and for validation.
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Affiliation(s)
- Tineke L Lenstra
- Laboratory of Receptor Biology and Gene Expression, Center for Cancer Research, National Cancer Institute, Bethesda, Maryland
| | - Daniel R Larson
- Laboratory of Receptor Biology and Gene Expression, Center for Cancer Research, National Cancer Institute, Bethesda, Maryland
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164
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Tethered Function Assays as Tools to Elucidate the Molecular Roles of RNA-Binding Proteins. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2016; 907:61-88. [PMID: 27256382 DOI: 10.1007/978-3-319-29073-7_3] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/15/2023]
Abstract
Dynamic regulation of RNA molecules is critical to the survival and development of cells. Messenger RNAs are transcribed in the nucleus as intron-containing pre-mRNAs and bound by RNA-binding proteins, which control their fate by regulating RNA stability, splicing, polyadenylation, translation, and cellular localization. Most RBPs have distinct mRNA-binding and functional domains; thus, the function of an RBP can be studied independently of RNA-binding by artificially recruiting the RBP to a reporter RNA and then measuring the effect of RBP recruitment on reporter splicing, stability, translational efficiency, or intracellular trafficking. These tethered function assays therefore do not require prior knowledge of the RBP's endogenous RNA targets or its binding sites within these RNAs. Here, we provide an overview of the experimental strategy and the strengths and limitations of common tethering systems. We illustrate specific examples of the application of the assay in elucidating the function of various classes of RBPs. We also discuss how classic tethering assay approaches and insights gained from them have been empowered by more recent technological advances, including efficient genome editing and high-throughput RNA-sequencing.
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165
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Martin RM, Rino J, de Jesus AC, Carmo-Fonseca M. Single-Molecule Live-Cell Visualization of Pre-mRNA Splicing. Methods Mol Biol 2016; 1358:335-50. [PMID: 26463395 DOI: 10.1007/978-1-4939-3067-8_22] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
Microscopy protocols that allow live-cell imaging of molecules and subcellular components tagged with fluorescent conjugates are indispensable in modern biological research. A breakthrough was recently introduced by the development of genetically encoded fluorescent tags that combined with fluorescence-based microscopic approaches of increasingly higher spatial and temporal resolution made it possible to detect single protein and nucleic acid molecules inside living cells. Here, we describe an approach to visualize single nascent pre-mRNA molecules and to measure in real time the dynamics of intron synthesis and excision.
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Affiliation(s)
- Robert M Martin
- Faculdade de Medicina, Instituto de Medicina Molecular, Universidade de Lisboa, Av. Prof. Egas Moniz, 1649-028, Lisbon, Portugal
| | - José Rino
- Faculdade de Medicina, Instituto de Medicina Molecular, Universidade de Lisboa, Av. Prof. Egas Moniz, 1649-028, Lisbon, Portugal
| | - Ana C de Jesus
- Faculdade de Medicina, Instituto de Medicina Molecular, Universidade de Lisboa, Av. Prof. Egas Moniz, 1649-028, Lisbon, Portugal
| | - Maria Carmo-Fonseca
- Faculdade de Medicina, Instituto de Medicina Molecular, Universidade de Lisboa, Av. Prof. Egas Moniz, 1649-028, Lisbon, Portugal.
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166
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Powrie EA, Ciocanel V, Kreiling JA, Gagnon JA, Sandstede B, Mowry KL. Using in vivo imaging to measure RNA mobility in Xenopus laevis oocytes. Methods 2015; 98:60-65. [PMID: 26546269 DOI: 10.1016/j.ymeth.2015.11.003] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/03/2015] [Revised: 11/01/2015] [Accepted: 11/03/2015] [Indexed: 01/05/2023] Open
Abstract
RNA localization in the Xenopus oocyte is responsible for the establishment of polarity during oogenesis as well as the specification of germ layers during embryogenesis. However, the inability to monitor mRNA localization in live vertebrate oocytes has posed a major barrier to understanding the mechanisms driving directional transport. Here we describe a method for imaging MS2 tagged RNA in live Xenopus oocytes to study the dynamics of RNA localization. We also focus on methods for implementing and analyzing FRAP data. This protocol is optimized for imaging of the RNAs in stage II oocytes but it can be adapted to study dynamics of other molecules during oogenesis. Using this approach, mobility can be measured in different regions of the oocyte, enabling the direct observation of molecular dynamics throughout the oocyte.
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Affiliation(s)
- Erin A Powrie
- Department of Molecular Biology, Cell Biology and Biochemistry, Brown University, Providence, RI 02912, USA
| | - Veronica Ciocanel
- Department of Applied Mathematics, Brown University, Providence, RI 02912, USA
| | - Jill A Kreiling
- Department of Molecular Biology, Cell Biology and Biochemistry, Brown University, Providence, RI 02912, USA
| | - James A Gagnon
- Department of Molecular and Cellular Biology, Harvard University, Cambridge, MA 02138, USA
| | - Bjӧrn Sandstede
- Department of Applied Mathematics, Brown University, Providence, RI 02912, USA
| | - Kimberly L Mowry
- Department of Molecular Biology, Cell Biology and Biochemistry, Brown University, Providence, RI 02912, USA.
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167
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Horn AE, Goodrich JA, Kugel JF. Single molecule studies of RNA polymerase II transcription in vitro. Transcription 2015; 5:e27608. [PMID: 25764112 DOI: 10.4161/trns.27608] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
Abstract
Eukaryotic mRNA transcription by RNA polymerase II (RNAP II) is the first step in gene expression and a key determinant of cellular regulation. Elucidating the mechanism by which RNAP II synthesizes RNA is therefore vital to determining how genes are controlled under diverse biological conditions. Significant advances in understanding RNAP II transcription have been achieved using classical biochemical and structural techniques; however, aspects of the transcription mechanism cannot be assessed using these approaches. The application of single-molecule techniques to study RNAP II transcription has provided new insight only obtainable by studying molecules in this complex system one at a time.
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Affiliation(s)
- Abigail E Horn
- a Department of Chemistry and Biochemistry; University of Colorado; Boulder, CO USA
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168
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Simultaneous detection of mRNA and protein in single cells using immunofluorescence-combined single-molecule RNA FISH. Biotechniques 2015; 59:209-12, 214, 216 passim. [PMID: 26458549 DOI: 10.2144/000114340] [Citation(s) in RCA: 40] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/06/2015] [Accepted: 07/28/2015] [Indexed: 11/23/2022] Open
Abstract
Although the concept of combining immunofluorescence (IF) with single-molecule RNA fluorescence in situ hybridization (smRNA FISH) seems obvious, the specific materials used during IF and smRNA FISH make it difficult to perform these procedures simultaneously on the same specimen. Even though there are reports where IF and smRNA FISH were combined with success, these were insufficient in terms of signal intensities, staining patterns, and GFP-compatibility, and a detailed exploration of the various factors that influence IF and smRNA FISH outcome has not been published yet. Here, we report a detailed study of conditions and reagents used in classic IF and smRNA FISH that allowed us to establish an easy, robust, and GFP-compatible procedure. Our protocol enables simultaneous detection of mRNA and protein quantity as well as the subcellular distribution of these molecules in single cells by combining an RNase-free modification of the IF technique and the more recent smRNA FISH method. Using this procedure, we have shown the direct interaction of RNase MCPIP1 with IL-6 mRNA. We also demonstrate the use of our protocol in heterogeneous cell population analysis, revealing cell-to-cell differences in mRNA and protein content.
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169
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Probing the dynamics of growth factor receptor by single-molecule fluorescence imaging. PROGRESS IN BIOPHYSICS AND MOLECULAR BIOLOGY 2015; 118:95-102. [DOI: 10.1016/j.pbiomolbio.2015.04.009] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/14/2015] [Revised: 04/22/2015] [Accepted: 04/24/2015] [Indexed: 12/14/2022]
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170
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Urbanek MO, Galka-Marciniak P, Olejniczak M, Krzyzosiak WJ. RNA imaging in living cells - methods and applications. RNA Biol 2015; 11:1083-95. [PMID: 25483044 PMCID: PMC4615301 DOI: 10.4161/rna.35506] [Citation(s) in RCA: 59] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022] Open
Abstract
Numerous types of transcripts perform multiple functions in cells, and these functions are mainly facilitated by the interactions of the RNA with various proteins and other RNAs. Insight into the dynamics of RNA biosynthesis, processing and cellular activities is highly desirable because this knowledge will deepen our understanding of cell physiology and help explain the mechanisms of RNA-mediated pathologies. In this review, we discuss the live RNA imaging systems that have been developed to date. We highlight information on the design of these systems, briefly discuss their advantages and limitations and provide examples of their numerous applications in various organisms and cell types. We present a detailed examination of one application of RNA imaging systems: this application aims to explain the role of mutant transcripts in human disease pathogenesis caused by triplet repeat expansions. Thus, this review introduces live RNA imaging systems and provides a glimpse into their various applications.
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Affiliation(s)
- Martyna O Urbanek
- a Department of Molecular Biomedicine; Institute of Bioorganic Chemistry; Polish Academy of Sciences ; Poznan , Poland
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171
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Bothma JP, Garcia HG, Ng S, Perry MW, Gregor T, Levine M. Enhancer additivity and non-additivity are determined by enhancer strength in the Drosophila embryo. eLife 2015; 4. [PMID: 26267217 PMCID: PMC4532966 DOI: 10.7554/elife.07956] [Citation(s) in RCA: 112] [Impact Index Per Article: 12.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2015] [Accepted: 07/15/2015] [Indexed: 01/29/2023] Open
Abstract
Metazoan genes are embedded in a rich milieu of regulatory information that often includes multiple enhancers possessing overlapping activities. In this study, we employ quantitative live imaging methods to assess the function of pairs of primary and shadow enhancers in the regulation of key patterning genes-knirps, hunchback, and snail-in developing Drosophila embryos. The knirps enhancers exhibit additive, sometimes even super-additive activities, consistent with classical gene fusion studies. In contrast, the hunchback enhancers function sub-additively in anterior regions containing saturating levels of the Bicoid activator, but function additively in regions where there are diminishing levels of the Bicoid gradient. Strikingly sub-additive behavior is also observed for snail, whereby removal of the proximal enhancer causes a significant increase in gene expression. Quantitative modeling of enhancer-promoter interactions suggests that weakly active enhancers function additively while strong enhancers behave sub-additively due to competition with the target promoter.
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Affiliation(s)
- Jacques P Bothma
- Department of Molecular and Cell Biology, University of California, Berkeley, Berkeley, United States
| | - Hernan G Garcia
- Department of Physics, Princeton University, Princeton, United States
| | - Samuel Ng
- Department of Molecular and Cell Biology, University of California, Berkeley, Berkeley, United States
| | - Michael W Perry
- Department of Molecular and Cell Biology, University of California, Berkeley, Berkeley, United States
| | - Thomas Gregor
- Department of Physics, Princeton University, Princeton, United States
| | - Michael Levine
- Department of Molecular and Cell Biology, University of California, Berkeley, Berkeley, United States
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172
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Mishin AS, Belousov VV, Solntsev KM, Lukyanov KA. Novel uses of fluorescent proteins. Curr Opin Chem Biol 2015; 27:1-9. [PMID: 26022943 DOI: 10.1016/j.cbpa.2015.05.002] [Citation(s) in RCA: 82] [Impact Index Per Article: 9.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2015] [Accepted: 05/07/2015] [Indexed: 11/28/2022]
Abstract
The field of genetically encoded fluorescent probes is developing rapidly. New chromophore structures were characterized in proteins of green fluorescent protein (GFP) family. A number of red fluorescent sensors, for example, for pH, Ca(2+) and H2O2, were engineered for multiparameter imaging. Progress in development of microscopy hardware and software together with specially designed FPs pushed superresolution fluorescence microscopy towards fast live-cell imaging. Deeper understanding of FPs structure and photophysics led to further development of imaging techniques. In addition to commonly used GFP-like proteins, unrelated types of FPs on the base of flavin-binding domains, bilirubin-binding domains or biliverdin-binding domains were designed. Their distinct biochemical and photophysical properties opened previously unexplored niches of FP uses such as labeling under anaerobic conditions, deep tissue imaging and even patients' blood analysis.
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Affiliation(s)
- Alexander S Mishin
- Institute of Bioorganic Chemistry, Miklukho-Maklaya 16/10, 117997 Moscow, Russia; Nizhny Novgorod State Medical Academy, Minin and Pozharsky Sq. 10/1, 603005 Nizhny Novgorod, Russia
| | - Vsevolod V Belousov
- Institute of Bioorganic Chemistry, Miklukho-Maklaya 16/10, 117997 Moscow, Russia
| | - Kyril M Solntsev
- School of Chemistry and Biochemistry, Georgia Institute of Technology, 901 Atlantic Drive, Atlanta, GA 30332-0400, United States
| | - Konstantin A Lukyanov
- Institute of Bioorganic Chemistry, Miklukho-Maklaya 16/10, 117997 Moscow, Russia; Nizhny Novgorod State Medical Academy, Minin and Pozharsky Sq. 10/1, 603005 Nizhny Novgorod, Russia.
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173
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Zoller B, Nicolas D, Molina N, Naef F. Structure of silent transcription intervals and noise characteristics of mammalian genes. Mol Syst Biol 2015. [PMID: 26215071 PMCID: PMC4547851 DOI: 10.15252/msb.20156257] [Citation(s) in RCA: 87] [Impact Index Per Article: 9.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022] Open
Abstract
Mammalian transcription occurs stochastically in short bursts interspersed by silent intervals showing a refractory period. However, the underlying processes and consequences on fluctuations in gene products are poorly understood. Here, we use single allele time-lapse recordings in mouse cells to identify minimal models of promoter cycles, which inform on the number and durations of rate-limiting steps responsible for refractory periods. The structure of promoter cycles is gene specific and independent of genomic location. Typically, five rate-limiting steps underlie the silent periods of endogenous promoters, while minimal synthetic promoters exhibit only one. Strikingly, endogenous or synthetic promoters with TATA boxes show simplified two-state promoter cycles. Since transcriptional bursting constrains intrinsic noise depending on the number of promoter steps, this explains why TATA box genes display increased intrinsic noise genome-wide in mammals, as revealed by single-cell RNA-seq. These findings have implications for basic transcription biology and shed light on interpreting single-cell RNA-counting experiments.
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Affiliation(s)
- Benjamin Zoller
- The Institute of Bioengineering, School of Life Sciences, Ecole Polytechnique Fédérale de Lausanne, Lausanne, Switzerland
| | - Damien Nicolas
- The Institute of Bioengineering, School of Life Sciences, Ecole Polytechnique Fédérale de Lausanne, Lausanne, Switzerland
| | - Nacho Molina
- The Institute of Bioengineering, School of Life Sciences, Ecole Polytechnique Fédérale de Lausanne, Lausanne, Switzerland
| | - Felix Naef
- The Institute of Bioengineering, School of Life Sciences, Ecole Polytechnique Fédérale de Lausanne, Lausanne, Switzerland
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174
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Walsh MT, Hsiao AP, Lee HS, Liu Z, Huang X. Capture and enumeration of mRNA transcripts from single cells using a microfluidic device. LAB ON A CHIP 2015; 15:2968-2980. [PMID: 26040942 DOI: 10.1039/c5lc00445d] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
Accurate measurement of RNA transcripts from single cells will enable the precise classification of cell types and characterization of the heterogeneity in cell populations that play key roles in normal cellular physiology and diseases. As a step towards this end, we have developed a microfluidic device and methods for automatic hydrodynamic capture of single mammalian cells and subsequent immobilization and digital counting of polyadenylated mRNA molecules released from the individual cells. Using single-molecule fluorescence imaging, we have demonstrated that polyadenylated mRNA molecules from single HeLa cells can be captured within minutes by hybridization to polydeoxyribothymidine oligonucleotides covalently attached on the glass surface in the device. The total mRNA molecule counts in the individual HeLa cells are found to vary significantly from one another. Our technology opens up the possibility of direct digital enumeration of RNA transcripts from single cells with single-molecule sensitivity using a single integrated microfluidic device.
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Affiliation(s)
- Matthew T Walsh
- Department of Bioengineering, University of California, San Diego, La Jolla, CA 92093, USA.
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175
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Arora A, Sunbul M, Jäschke A. Dual-colour imaging of RNAs using quencher- and fluorophore-binding aptamers. Nucleic Acids Res 2015; 43:e144. [PMID: 26175046 PMCID: PMC4666381 DOI: 10.1093/nar/gkv718] [Citation(s) in RCA: 47] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2015] [Accepted: 07/02/2015] [Indexed: 01/12/2023] Open
Abstract
In order to gain deeper insight into the functions and dynamics of RNA in cells, the development of methods for imaging multiple RNAs simultaneously is of paramount importance. Here, we describe a modular approach to image RNA in living cells using an RNA aptamer that binds to dinitroaniline, an efficient general contact quencher. Dinitroaniline quenches the fluorescence of different fluorophores when directly conjugated to them via ethylene glycol linkers by forming a non-fluorescent intramolecular complex. Since the binding of the RNA aptamer to the quencher destroys the fluorophore-quencher complex, fluorescence increases dramatically upon binding. Using this principle, a series of fluorophores were turned into fluorescent turn-on probes by conjugating them to dinitroaniline. These probes ranged from fluorescein-dinitroaniline (green) to TexasRed-dinitroaniline (red) spanning across the visible spectrum. The dinitroaniline-binding aptamer (DNB) was generated by in vitro selection, and was found to bind all probes, leading to fluorescence increase in vitro and in living cells. When expressed in E. coli, the DNB aptamer could be labelled and visualized with different-coloured fluorophores and therefore it can be used as a genetically encoded tag to image target RNAs. Furthermore, combining contact-quenched fluorogenic probes with orthogonal DNB (the quencher-binding RNA aptamer) and SRB-2 aptamers (a fluorophore-binding RNA aptamer) allowed dual-colour imaging of two different fluorescence-enhancing RNA tags in living cells, opening new avenues for studying RNA co-localization and trafficking.
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Affiliation(s)
- Ankita Arora
- Institute of Pharmacy and Molecular Biotechnology, Heidelberg University, Im Neuenheimer Feld 364, Heidelberg 69120, Germany
| | - Murat Sunbul
- Institute of Pharmacy and Molecular Biotechnology, Heidelberg University, Im Neuenheimer Feld 364, Heidelberg 69120, Germany
| | - Andres Jäschke
- Institute of Pharmacy and Molecular Biotechnology, Heidelberg University, Im Neuenheimer Feld 364, Heidelberg 69120, Germany
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176
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Bajon E, Laterreur N, Wellinger RJ. A Single Templating RNA in Yeast Telomerase. Cell Rep 2015; 12:441-8. [PMID: 26166570 DOI: 10.1016/j.celrep.2015.06.045] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/15/2015] [Revised: 06/04/2015] [Accepted: 06/13/2015] [Indexed: 12/31/2022] Open
Abstract
The number of essential telomerase components in the active ribonucleoprotein (RNP) has important implications for its mechanism of action yet is by and large unknown. We report that two differentially tagged TLC1 RNAs endogenously expressed in a heterozygous diploid and simultaneously detected via multi-color fluorescence in situ hybridization (FISH) experiments do not co-localize. Probabilistic calculations combined with direct quantification of FISH signals demonstrate that the TLC1 RNA indeed occurs as a single molecule in these RNPs. In addition, two differentially tagged reverse-transcriptase subunits could not be co-immunoprecipitated. These results therefore show that, in yeast cells, telomerase is assembled and matured and occurs as a monomer when not on telomeres. Finally, combining these findings with previous evidence leads us to propose that the enzyme also acts as a monomer when elongating telomeres.
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Affiliation(s)
- Emmanuel Bajon
- Department of Microbiology and Infectious Diseases, Faculty of Medicine, Université de Sherbrooke, 3201, rue Jean Mignault, Sherbrooke, QC J1E 4K8, Canada
| | - Nancy Laterreur
- Department of Microbiology and Infectious Diseases, Faculty of Medicine, Université de Sherbrooke, 3201, rue Jean Mignault, Sherbrooke, QC J1E 4K8, Canada
| | - Raymund J Wellinger
- Department of Microbiology and Infectious Diseases, Faculty of Medicine, Université de Sherbrooke, 3201, rue Jean Mignault, Sherbrooke, QC J1E 4K8, Canada.
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177
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Schmid M, Olszewski P, Pelechano V, Gupta I, Steinmetz LM, Jensen TH. The Nuclear PolyA-Binding Protein Nab2p Is Essential for mRNA Production. Cell Rep 2015; 12:128-139. [PMID: 26119729 DOI: 10.1016/j.celrep.2015.06.008] [Citation(s) in RCA: 38] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/10/2015] [Revised: 05/13/2015] [Accepted: 06/01/2015] [Indexed: 10/23/2022] Open
Abstract
Polyadenylation of mRNA is a key step in eukaryotic gene expression. However, despite the major impact of poly(A) tails on mRNA metabolism, the precise roles of poly(A)-binding proteins (PABPs) in nuclear mRNA biogenesis remain elusive. Here, we demonstrate that rapid nuclear depletion of the S. cerevisiae PABP Nab2p leads to a global loss of cellular mRNA, but not of RNA lacking poly(A) tails. Disappearance of mRNA is a nuclear event, but not due to decreased transcription. Instead, the absence of Nab2p results in robust nuclear mRNA decay by the ribonucleolytic RNA exosome in a polyadenylation-dependent process. We conclude that Nab2p is required to protect early mRNA and therefore constitutes a crucial nuclear mRNA biogenesis factor.
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Affiliation(s)
- Manfred Schmid
- Centre for mRNP Biogenesis and Metabolism, Department of Molecular Biology and Genetics, Aarhus University, C.F. Møllers Alle 3, Building 1130, 8000 Aarhus C., Denmark.
| | - Pawel Olszewski
- Centre for mRNP Biogenesis and Metabolism, Department of Molecular Biology and Genetics, Aarhus University, C.F. Møllers Alle 3, Building 1130, 8000 Aarhus C., Denmark
| | - Vicent Pelechano
- European Molecular Biology Laboratory (EMBL), Genome Biology Unit, 69117 Heidelberg, Germany
| | - Ishaan Gupta
- European Molecular Biology Laboratory (EMBL), Genome Biology Unit, 69117 Heidelberg, Germany
| | - Lars M Steinmetz
- European Molecular Biology Laboratory (EMBL), Genome Biology Unit, 69117 Heidelberg, Germany; Stanford Genome Technology Center, Stanford University, Palo Alto, CA 94304, USA; Department of Genetics, Stanford University School of Medicine, Stanford, CA 94305, USA
| | - Torben Heick Jensen
- Centre for mRNP Biogenesis and Metabolism, Department of Molecular Biology and Genetics, Aarhus University, C.F. Møllers Alle 3, Building 1130, 8000 Aarhus C., Denmark.
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178
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Ochiai H, Sugawara T, Yamamoto T. Simultaneous live imaging of the transcription and nuclear position of specific genes. Nucleic Acids Res 2015; 43:e127. [PMID: 26092696 PMCID: PMC4627063 DOI: 10.1093/nar/gkv624] [Citation(s) in RCA: 68] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2015] [Accepted: 06/04/2015] [Indexed: 12/14/2022] Open
Abstract
The relationship between genome organization and gene expression has recently been established. However, the relationships between spatial organization, dynamics, and transcriptional regulation of the genome remain unknown. In this study, we developed a live-imaging method for simultaneous measurements of the transcriptional activity and nuclear position of endogenous genes, which we termed the ‘Real-time Observation of Localization and EXpression (ROLEX)’ system. We demonstrated that ROLEX is highly specific and does not affect the expression level of the target gene. ROLEX enabled detection of sub-genome-wide mobility changes that depended on the state of Nanog transactivation in embryonic stem cells. We believe that the ROLEX system will become a powerful tool for exploring the relationship between transcription and nuclear dynamics in living cells.
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Affiliation(s)
- Hiroshi Ochiai
- Research Center for the Mathematics on Chromatin Live Dynamics (RcMcD), Hiroshima University, Higashi-Hiroshima 739-8530, Japan
| | - Takeshi Sugawara
- Research Center for the Mathematics on Chromatin Live Dynamics (RcMcD), Hiroshima University, Higashi-Hiroshima 739-8530, Japan
| | - Takashi Yamamoto
- Research Center for the Mathematics on Chromatin Live Dynamics (RcMcD), Hiroshima University, Higashi-Hiroshima 739-8530, Japan Department of Mathematical and Life Sciences, Graduate School of Science, Hiroshima University, Higashi-Hiroshima 739-8526, Japan
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179
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Abstract
Recently, major progress has been made to develop computational models to predict and explain the mechanisms and behaviors of gene regulation. Here, we review progress on how these mechanisms and behaviors have been interpreted with analog models, where cell properties continuously modulate transcription, and digital models, where gene modulation involves discrete activation and inactivation events. We introduce recent experimental approaches, which measure these gene regulatory behaviors at single-cell and single-molecule resolution, and we discuss the integration of these approaches with computational models to reveal biophysical insight. By analyzing simple toy models in the context of existing experimental capabilities, we discuss the interplay between different experiments and different models to measure and interpret gene regulatory behaviors. Finally, we review recent successes in the development of predictive computational models for the control of gene regulation behaviors.
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Affiliation(s)
- Brian Munsky
- Department of Chemical and Biological Engineering, Colorado State University, Fort Collins, CO 80523, USA. School of Biomedical Engineering, Colorado State University, Fort Collins, CO 80526, USA
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180
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Silva AM, Brown JM, Buckle VJ, Wade-Martins R, Lufino MMP. Expanded GAA repeats impair FXN gene expression and reposition the FXN locus to the nuclear lamina in single cells. Hum Mol Genet 2015; 24:3457-71. [PMID: 25814655 PMCID: PMC4498154 DOI: 10.1093/hmg/ddv096] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2015] [Accepted: 03/12/2015] [Indexed: 02/07/2023] Open
Abstract
Abnormally expanded DNA repeats are associated with several neurodegenerative diseases. In Friedreich's ataxia (FRDA), expanded GAA repeats in intron 1 of the frataxin gene (FXN) reduce FXN mRNA levels in averaged cell samples through a poorly understood mechanism. By visualizing FXN expression and nuclear localization in single cells, we show that GAA-expanded repeats decrease the number of FXN mRNA molecules, slow transcription, and increase FXN localization at the nuclear lamina (NL). Restoring histone acetylation reverses NL positioning. Expanded GAA-FXN loci in FRDA patient cells show increased NL localization with increased silencing of alleles and reduced transcription from alleles positioned peripherally. We also demonstrate inefficiencies in transcription initiation and elongation from the expanded GAA-FXN locus at single-cell resolution. We suggest that repressive epigenetic modifications at the expanded GAA-FXN locus may lead to NL relocation, where further repression may occur.
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Affiliation(s)
- Ana M Silva
- Department of Physiology, Anatomy and Genetics, University of Oxford, Oxford OX1 3QX, UK, Faculdade de Medicina, Universidade de Lisboa, Lisboa 1649-028, Portugal and
| | - Jill M Brown
- Medical Research Council, Molecular Haematology Unit, Weatherall Institute of Molecular Medicine, University of Oxford, Oxford OX3 9DS, UK
| | - Veronica J Buckle
- Medical Research Council, Molecular Haematology Unit, Weatherall Institute of Molecular Medicine, University of Oxford, Oxford OX3 9DS, UK
| | - Richard Wade-Martins
- Department of Physiology, Anatomy and Genetics, University of Oxford, Oxford OX1 3QX, UK,
| | - Michele M P Lufino
- Department of Physiology, Anatomy and Genetics, University of Oxford, Oxford OX1 3QX, UK,
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181
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Buxbaum AR, Yoon YJ, Singer RH, Park HY. Single-molecule insights into mRNA dynamics in neurons. Trends Cell Biol 2015; 25:468-75. [PMID: 26052005 DOI: 10.1016/j.tcb.2015.05.005] [Citation(s) in RCA: 51] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/07/2015] [Revised: 05/07/2015] [Accepted: 05/08/2015] [Indexed: 10/23/2022]
Abstract
Targeting of mRNAs to neuronal dendrites and axons plays an integral role in intracellular signaling, development, and synaptic plasticity. Single-molecule imaging of mRNAs in neurons and brain tissue has led to enhanced understanding of mRNA dynamics. Here we discuss aspects of mRNA regulation as revealed by single-molecule detection, which has led to quantitative analyses of mRNA diversity, localization, transport, and translation. These exciting new discoveries propel our understanding of the life of an mRNA in a neuron and how its activity is regulated at the single-molecule level.
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Affiliation(s)
- Adina R Buxbaum
- Department of Anatomy and Structural Biology, Albert Einstein College of Medicine, 1300 Morris Park Avenue, Bronx, NY 10461, USA; Gruss Lipper Biophotonics Center, Albert Einstein College of Medicine, 1300 Morris Park Avenue, Bronx, NY 10461, USA; Janelia Farm Research Campus, Howard Hughes Medical Institute, 19700 Helix Drive, Ashburn, VA 20147, USA
| | - Young J Yoon
- Department of Anatomy and Structural Biology, Albert Einstein College of Medicine, 1300 Morris Park Avenue, Bronx, NY 10461, USA
| | - Robert H Singer
- Department of Anatomy and Structural Biology, Albert Einstein College of Medicine, 1300 Morris Park Avenue, Bronx, NY 10461, USA; Gruss Lipper Biophotonics Center, Albert Einstein College of Medicine, 1300 Morris Park Avenue, Bronx, NY 10461, USA; Janelia Farm Research Campus, Howard Hughes Medical Institute, 19700 Helix Drive, Ashburn, VA 20147, USA
| | - Hye Yoon Park
- Janelia Farm Research Campus, Howard Hughes Medical Institute, 19700 Helix Drive, Ashburn, VA 20147, USA; Department of Physics and Astronomy, Seoul National University, Seoul 151-747, Korea; Institute of Molecular Biology and Genetics, Seoul National University, Seoul 151-742, Korea.
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182
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Velten L, Anders S, Pekowska A, Järvelin AI, Huber W, Pelechano V, Steinmetz LM. Single-cell polyadenylation site mapping reveals 3' isoform choice variability. Mol Syst Biol 2015; 11:812. [PMID: 26040288 PMCID: PMC4501847 DOI: 10.15252/msb.20156198] [Citation(s) in RCA: 48] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
Abstract
Cell-to-cell variability in gene expression is important for many processes in biology, including embryonic development and stem cell homeostasis. While heterogeneity of gene expression levels has been extensively studied, less attention has been paid to mRNA polyadenylation isoform choice. 3′ untranslated regions regulate mRNA fate, and their choice is tightly controlled during development, but how 3′ isoform usage varies within genetically and developmentally homogeneous cell populations has not been explored. Here, we perform genome-wide quantification of polyadenylation site usage in single mouse embryonic and neural stem cells using a novel single-cell transcriptomic method, BATSeq. By applying BATBayes, a statistical framework for analyzing single-cell isoform data, we find that while the developmental state of the cell globally determines isoform usage, single cells from the same state differ in the choice of isoforms. Notably this variation exceeds random selection with equal preference in all cells, a finding that was confirmed by RNA FISH data. Variability in 3′ isoform choice has potential implications on functional cell-to-cell heterogeneity as well as utility in resolving cell populations.
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Affiliation(s)
- Lars Velten
- European Molecular Biology Laboratory, Genome Biology Unit, Heidelberg, Germany
| | - Simon Anders
- European Molecular Biology Laboratory, Genome Biology Unit, Heidelberg, Germany
| | - Aleksandra Pekowska
- European Molecular Biology Laboratory, Genome Biology Unit, Heidelberg, Germany
| | - Aino I Järvelin
- European Molecular Biology Laboratory, Genome Biology Unit, Heidelberg, Germany
| | - Wolfgang Huber
- European Molecular Biology Laboratory, Genome Biology Unit, Heidelberg, Germany
| | - Vicent Pelechano
- European Molecular Biology Laboratory, Genome Biology Unit, Heidelberg, Germany
| | - Lars M Steinmetz
- European Molecular Biology Laboratory, Genome Biology Unit, Heidelberg, Germany Stanford Genome Technology Center, Palo Alto, CA, USA Department of Genetics, Stanford University School of Medicine, Stanford, CA, USA
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183
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Promoter-Autonomous Functioning in a Controlled Environment using Single Molecule FISH. Sci Rep 2015; 5:9934. [PMID: 26017315 PMCID: PMC4446897 DOI: 10.1038/srep09934] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/31/2014] [Accepted: 03/11/2015] [Indexed: 11/09/2022] Open
Abstract
Transcription is a highly regulated biological process, initiated through the assembly of complexes at the promoter that contain both the general transcriptional machinery and promoter-specific factors. Despite the abundance of studies focusing on transcription, certain questions have remained unanswered. It is not clear how the transcriptional profile of a promoter is affected by genomic context. Also, there is no single cell method to directly compare transcriptional profiles independent of gene length and sequence. In this work, we employ a single genetic site for isolating the transcriptional kinetics of yeast promoters. Utilizing single molecule FISH, we directly compare the transcriptional activity of different promoters, considering both synthesis and cell-to-cell variability. With this approach, we provide evidence suggesting promoters autonomously encode their associated transcriptional profiles, independent of genomic locus, gene length and gene sequence.
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184
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Oeffinger M, Montpetit B. Emerging properties of nuclear RNP biogenesis and export. Curr Opin Cell Biol 2015; 34:46-53. [PMID: 25938908 DOI: 10.1016/j.ceb.2015.04.007] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/26/2014] [Revised: 03/23/2015] [Accepted: 04/14/2015] [Indexed: 01/02/2023]
Abstract
RNA biology has recently seen an explosion of data due to advances in RNA sequencing, proteomic, and RNA imaging technologies. In this review, we highlight progress that has been made using these approaches in the area of nuclear RNP biogenesis and export. Excitingly, the ability to collect quantitative data at the 'omics' scale combined with measurements of transcription, decay, and transport kinetics is providing the information needed to address RNP biogenesis at a systems level. We believe this to be a necessary and critical next step that will lead to a better understanding of how RNP quality, diversity, and fate emerge from a defined set of nuclear RNP assembly and maturation steps.
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Affiliation(s)
- Marlene Oeffinger
- Institut de recherches cliniques de Montréal, 110 Avenue des Pins Ouest, Montréal, Québec, Canada H2W 1R7; Département de biochimie et médicine moléculaire, Université de Montréal, Montréal, Québec, Canada H3T 1J4; Faculty of Medicine, Division of Experimental Medicine, McGill University, Montréal, Québec, Canada H3A 1A3.
| | - Ben Montpetit
- Department of Cell Biology, University of Alberta, 5-14 Medical Sciences Building, Edmonton, Alberta, Canada T6G 2H7.
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185
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Cheglakov Z, Cronin TM, He C, Weizmann Y. Live Cell MicroRNA Imaging Using Cascade Hybridization Reaction. J Am Chem Soc 2015; 137:6116-9. [PMID: 25932784 DOI: 10.1021/jacs.5b01451] [Citation(s) in RCA: 195] [Impact Index Per Article: 21.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
Recent advances in RNA research have posed new directives in biology and chemistry to uncover the complex roles of ribonucleic acids in cellular processes. Innovative techniques to visualize native RNAs, particularly, short, low-abundance RNAs in live cells, can dramatically impact current research on the roles of RNAs in biology. Herein, we report a novel method for real-time, microRNA imaging inside live cells based on programmable oligonucleotide probes, which self-assemble through the Cascade Hybridization Reaction (CHR).
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Affiliation(s)
- Zoya Cheglakov
- ‡Department of Chemistry and Institute for Biophysical Dynamics, The University of Chicago, 929 East 57th Street, Chicago, Illinois 60637, United States
| | - Timothy M Cronin
- †Department of Chemistry, The University of Chicago, 929 East 57th Street, Chicago, Illinois 60637, United States
| | - Chuan He
- ‡Department of Chemistry and Institute for Biophysical Dynamics, The University of Chicago, 929 East 57th Street, Chicago, Illinois 60637, United States
| | - Yossi Weizmann
- †Department of Chemistry, The University of Chicago, 929 East 57th Street, Chicago, Illinois 60637, United States
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186
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Liu Z, Lavis L, Betzig E. Imaging Live-Cell Dynamics and Structure at the Single-Molecule Level. Mol Cell 2015; 58:644-59. [DOI: 10.1016/j.molcel.2015.02.033] [Citation(s) in RCA: 353] [Impact Index Per Article: 39.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/16/2023]
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187
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Abstract
mRNA localisation coupled to translational regulation provides an important means of dictating when and where proteins function in a variety of model systems. This mechanism is particularly relevant in polarised or migrating cells. Although many of the models for how this is achieved were first proposed over 20 years ago, some of the molecular details are still poorly understood. Nevertheless, advanced imaging, biochemical and computational approaches have started to shed light on the cis-acting localisation signals and trans-acting factors that dictate the final destination of localised transcripts. In this Cell Science at a Glance article and accompanying poster, we provide an overview of mRNA localisation, from transcription to degradation, focusing on the microtubule-dependent active transport and anchoring mechanism, which we will use to explain the general paradigm. However, it is clear that there are diverse ways in which mRNAs become localised and target protein expression, and we highlight some of the similarities and differences between these mechanisms.
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Affiliation(s)
- Richard M Parton
- Department of Biochemistry, University of Oxford, South Parks Road, Oxford OX1 3QU, UK
| | - Alexander Davidson
- Department of Biochemistry, University of Oxford, South Parks Road, Oxford OX1 3QU, UK
| | - Ilan Davis
- Department of Biochemistry, University of Oxford, South Parks Road, Oxford OX1 3QU, UK
| | - Timothy T Weil
- Department of Zoology, University of Cambridge, Downing Street, Cambridge CB2 3EJ, UK
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188
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Wu B, Miskolci V, Sato H, Tutucci E, Kenworthy CA, Donnelly SK, Yoon YJ, Cox D, Singer RH, Hodgson L. Synonymous modification results in high-fidelity gene expression of repetitive protein and nucleotide sequences. Genes Dev 2015; 29:876-86. [PMID: 25877922 PMCID: PMC4403262 DOI: 10.1101/gad.259358.115] [Citation(s) in RCA: 73] [Impact Index Per Article: 8.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/26/2015] [Accepted: 03/18/2015] [Indexed: 01/30/2023]
Abstract
Repetitive nucleotide or amino acid sequences are often engineered into probes and biosensors to achieve functional readouts and robust signal amplification, but these repeated sequences are notoriously prone to aberrant deletion and degradation. Wu et al. developed an approach to solve this problem by modifying the nucleotide sequences of the target mRNA to make them nonrepetitive but still functional (“synonymous”). Using the synonymous modification to FRET biosensors, they achieved correct expression of full-length sensors and found that the biological interpretations of the sensor are significantly different when a correct, full-length biosensor is expressed. Repetitive nucleotide or amino acid sequences are often engineered into probes and biosensors to achieve functional readouts and robust signal amplification. However, these repeated sequences are notoriously prone to aberrant deletion and degradation, impacting the ability to correctly detect and interpret biological functions. Here, we introduce a facile and generalizable approach to solve this often unappreciated problem by modifying the nucleotide sequences of the target mRNA to make them nonrepetitive but still functional (“synonymous”). We first demonstrated the procedure by designing a cassette of synonymous MS2 RNA motifs and tandem coat proteins for RNA imaging and showed a dramatic improvement in signal and reproducibility in single-RNA detection in live cells. The same approach was extended to enhancing the stability of engineered fluorescent biosensors containing a fluorescent resonance energy transfer (FRET) pair of fluorescent proteins on which a great majority of systems thus far in the field are based. Using the synonymous modification to FRET biosensors, we achieved correct expression of full-length sensors, eliminating the aberrant truncation products that often were assumed to be due to nonspecific proteolytic cleavages. Importantly, the biological interpretations of the sensor are significantly different when a correct, full-length biosensor is expressed. Thus, we show here a useful and generally applicable method to maintain the integrity of expressed genes, critical for the correct interpretation of probe readouts.
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Affiliation(s)
- Bin Wu
- Department of Anatomy and Structural Biology, Albert Einstein College of Medicine, Bronx, New York 10461, USA; Gruss-Lipper Biophotonics Center, Albert Einstein College of Medicine, Bronx, New York 10461, USA
| | - Veronika Miskolci
- Department of Anatomy and Structural Biology, Albert Einstein College of Medicine, Bronx, New York 10461, USA
| | - Hanae Sato
- Department of Anatomy and Structural Biology, Albert Einstein College of Medicine, Bronx, New York 10461, USA
| | - Evelina Tutucci
- Department of Anatomy and Structural Biology, Albert Einstein College of Medicine, Bronx, New York 10461, USA
| | - Charles A Kenworthy
- Department of Anatomy and Structural Biology, Albert Einstein College of Medicine, Bronx, New York 10461, USA
| | - Sara K Donnelly
- Department of Anatomy and Structural Biology, Albert Einstein College of Medicine, Bronx, New York 10461, USA; Gruss-Lipper Biophotonics Center, Albert Einstein College of Medicine, Bronx, New York 10461, USA
| | - Young J Yoon
- Department of Anatomy and Structural Biology, Albert Einstein College of Medicine, Bronx, New York 10461, USA
| | - Dianne Cox
- Department of Anatomy and Structural Biology, Albert Einstein College of Medicine, Bronx, New York 10461, USA; Gruss-Lipper Biophotonics Center, Albert Einstein College of Medicine, Bronx, New York 10461, USA
| | - Robert H Singer
- Department of Anatomy and Structural Biology, Albert Einstein College of Medicine, Bronx, New York 10461, USA; Gruss-Lipper Biophotonics Center, Albert Einstein College of Medicine, Bronx, New York 10461, USA
| | - Louis Hodgson
- Department of Anatomy and Structural Biology, Albert Einstein College of Medicine, Bronx, New York 10461, USA; Gruss-Lipper Biophotonics Center, Albert Einstein College of Medicine, Bronx, New York 10461, USA
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189
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Halstead JM, Lionnet T, Wilbertz JH, Wippich F, Ephrussi A, Singer RH, Chao JA. Translation. An RNA biosensor for imaging the first round of translation from single cells to living animals. Science 2015; 347:1367-671. [PMID: 25792328 DOI: 10.1126/science.aaa3380] [Citation(s) in RCA: 198] [Impact Index Per Article: 22.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
Analysis of single molecules in living cells has provided quantitative insights into the kinetics of fundamental biological processes; however, the dynamics of messenger RNA (mRNA) translation have yet to be addressed. We have developed a fluorescence microscopy technique that reports on the first translation events of individual mRNA molecules. This allowed us to examine the spatiotemporal regulation of translation during normal growth and stress and during Drosophila oocyte development. We have shown that mRNAs are not translated in the nucleus but translate within minutes after export, that sequestration within P-bodies regulates translation, and that oskar mRNA is not translated until it reaches the posterior pole of the oocyte. This methodology provides a framework for studying initiation of protein synthesis on single mRNAs in living cells.
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Affiliation(s)
- James M Halstead
- Friedrich Miescher Institute for Biomedical Research, CH-4058 Basel, Switzerland
| | - Timothée Lionnet
- Department of Anatomy and Structural Biology, Albert Einstein College of Medicine, Bronx, NY 10461, USA. Gruss-Lipper Biophotonics Center, Albert Einstein College of Medicine, Bronx, NY 10461, USA. Transcription Imaging Consortium, Howard Hughes Medical Institute Janelia Farm Research Campus, Ashburn, VA 20147, USA
| | - Johannes H Wilbertz
- Friedrich Miescher Institute for Biomedical Research, CH-4058 Basel, Switzerland. University of Basel, CH-4003 Basel, Switzerland
| | - Frank Wippich
- Developmental Biology Unit, European Molecular Biology Laboratory, 69117 Heidelberg, Germany
| | - Anne Ephrussi
- Developmental Biology Unit, European Molecular Biology Laboratory, 69117 Heidelberg, Germany.
| | - Robert H Singer
- Department of Anatomy and Structural Biology, Albert Einstein College of Medicine, Bronx, NY 10461, USA. Gruss-Lipper Biophotonics Center, Albert Einstein College of Medicine, Bronx, NY 10461, USA. Transcription Imaging Consortium, Howard Hughes Medical Institute Janelia Farm Research Campus, Ashburn, VA 20147, USA.
| | - Jeffrey A Chao
- Friedrich Miescher Institute for Biomedical Research, CH-4058 Basel, Switzerland. Department of Anatomy and Structural Biology, Albert Einstein College of Medicine, Bronx, NY 10461, USA.
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190
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Martinho RG, Guilgur LG, Prudêncio P. How gene expression in fast-proliferating cells keeps pace. Bioessays 2015; 37:514-24. [PMID: 25823409 DOI: 10.1002/bies.201400195] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
The development of living organisms requires a precise coordination of all basic cellular processes, in space and time. Early embryogenesis of most species with externally deposited eggs starts with a series of extremely fast cleavage cycles. These divisions have a strong influence on gene expression as mitosis represses transcription and pre-mRNA processing. In this review, we will describe the distinct adaptations for efficient gene expression and discuss the emerging role of the multifunctional NineTeen Complex (NTC) in gene expression and genomic stability during fast proliferation.
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Affiliation(s)
- Rui G Martinho
- Departamento de Ciências Biomédicas e Medicina, Regenerative Medicine Program, Universidade do Algarve, Campus de Gambelas, Faro, Portugal; Center for Biomedical Research, Universidade do Algarve, Campus de Gambelas, Faro, Portugal; Instituto Gulbenkian de Ciência, Oeiras, Portugal
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191
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Annibale P, Gratton E. Single cell visualization of transcription kinetics variance of highly mobile identical genes using 3D nanoimaging. Sci Rep 2015; 5:9258. [PMID: 25788248 PMCID: PMC4365385 DOI: 10.1038/srep09258] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2014] [Accepted: 02/25/2015] [Indexed: 12/11/2022] Open
Abstract
Multi-cell biochemical assays and single cell fluorescence measurements revealed that the elongation rate of Polymerase II (PolII) in eukaryotes varies largely across different cell types and genes. However, there is not yet a consensus whether intrinsic factors such as the position, local mobility or the engagement by an active molecular mechanism of a genetic locus could be the determinants of the observed heterogeneity. Here by employing high-speed 3D fluorescence nanoimaging techniques we resolve and track at the single cell level multiple, distinct regions of mRNA synthesis within the model system of a large transgene array. We demonstrate that these regions are active transcription sites that release mRNA molecules in the nucleoplasm. Using fluctuation spectroscopy and the phasor analysis approach we were able to extract the local PolII elongation rate at each site as a function of time. We measured a four-fold variation in the average elongation between identical copies of the same gene measured simultaneously within the same cell, demonstrating a correlation between local transcription kinetics and the movement of the transcription site. Together these observations demonstrate that local factors, such as chromatin local mobility and the microenvironment of the transcription site, are an important source of transcription kinetics variability.
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Affiliation(s)
- Paolo Annibale
- Laboratory for Fluorescence Dynamics, Department of Biomedical Engineering, University of California Irvine
| | - Enrico Gratton
- Laboratory for Fluorescence Dynamics, Department of Biomedical Engineering, University of California Irvine
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192
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Campbell PD, Chao JA, Singer RH, Marlow FL. Dynamic visualization of transcription and RNA subcellular localization in zebrafish. Development 2015; 142:1368-74. [PMID: 25758462 DOI: 10.1242/dev.118968] [Citation(s) in RCA: 41] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
Live imaging of transcription and RNA dynamics has been successful in cultured cells and tissues of vertebrates but is challenging to accomplish in vivo. The zebrafish offers important advantages to study these processes--optical transparency during embryogenesis, genetic tractability and rapid development. Therefore, to study transcription and RNA dynamics in an intact vertebrate organism, we have adapted the MS2 RNA-labeling system to zebrafish. By using this binary system to coexpress a fluorescent MS2 bacteriophage coat protein (MCP) and an RNA of interest tagged with multiple copies of the RNA hairpin MS2-binding site (MBS), live-cell imaging of RNA dynamics at single RNA molecule resolution has been achieved in other organisms. Here, using a Gateway-compatible MS2 labeling system, we generated stable transgenic zebrafish lines expressing MCP, validated the MBS-MCP interaction and applied the system to investigate zygotic genome activation (ZGA) and RNA localization in primordial germ cells (PGCs) in zebrafish. Although cleavage stage cells are initially transcriptionally silent, we detect transcription of MS2-tagged transcripts driven by the βactin promoter at ∼ 3-3.5 h post-fertilization, consistent with the previously reported ZGA. Furthermore, we show that MS2-tagged nanos3 3'UTR transcripts localize to PGCs, where they are diffusely cytoplasmic and within larger cytoplasmic accumulations reminiscent of those displayed by endogenous nanos3. These tools provide a new avenue for live-cell imaging of RNA molecules in an intact vertebrate. Together with new techniques for targeted genome editing, this system will be a valuable tool to tag and study the dynamics of endogenous RNAs during zebrafish developmental processes.
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Affiliation(s)
- Philip D Campbell
- Department of Developmental and Molecular Biology, Albert Einstein College of Medicine, Yeshiva University, 1300 Morris Park Av, Bronx, NY 10461, USA
| | - Jeffrey A Chao
- Department of Anatomy and Structural Biology, Albert Einstein College of Medicine, Yeshiva University, 1300 Morris Park Av, Bronx, NY 10461, USA Friedrich Meischer Institute for Biomedical Research, Maulbeerstrasse 66, Basel 4058, Switzerland
| | - Robert H Singer
- Department of Anatomy and Structural Biology, Albert Einstein College of Medicine, Yeshiva University, 1300 Morris Park Av, Bronx, NY 10461, USA Department of Neuroscience, Albert Einstein College of Medicine, Yeshiva University, 1300 Morris Park Av, Bronx, NY 10461, USA Department of Cell Biology, Albert Einstein College of Medicine, Yeshiva University, 1300 Morris Park Av, Bronx, NY 10461, USA
| | - Florence L Marlow
- Department of Developmental and Molecular Biology, Albert Einstein College of Medicine, Yeshiva University, 1300 Morris Park Av, Bronx, NY 10461, USA Department of Neuroscience, Albert Einstein College of Medicine, Yeshiva University, 1300 Morris Park Av, Bronx, NY 10461, USA
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193
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Rino J, Martin RM, Carvalho C, de Jesus AC, Carmo-Fonseca M. Single-Molecule Imaging of RNA Splicing in Live Cells. Methods Enzymol 2015; 558:571-585. [PMID: 26068754 DOI: 10.1016/bs.mie.2015.01.013] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
Expression of genetic information in eukaryotes involves a series of interconnected processes that ultimately determine the quality and amount of proteins in the cell. Many individual steps in gene expression are kinetically coupled, but tools are lacking to determine how temporal relationships between chemical reactions contribute to the output of the final gene product. Here, we describe a strategy that permits direct measurements of intron dynamics in single pre-mRNA molecules in live cells. This approach reveals that splicing can occur much faster than previously proposed and opens new avenues for studying how kinetic mechanisms impact on RNA biogenesis.
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Affiliation(s)
- José Rino
- Instituto de Medicina Molecular, Faculdade de Medicina, Universidade de Lisboa, Lisboa, Portugal
| | - Robert M Martin
- Instituto de Medicina Molecular, Faculdade de Medicina, Universidade de Lisboa, Lisboa, Portugal
| | - Célia Carvalho
- Instituto de Medicina Molecular, Faculdade de Medicina, Universidade de Lisboa, Lisboa, Portugal
| | - Ana C de Jesus
- Instituto de Medicina Molecular, Faculdade de Medicina, Universidade de Lisboa, Lisboa, Portugal
| | - Maria Carmo-Fonseca
- Instituto de Medicina Molecular, Faculdade de Medicina, Universidade de Lisboa, Lisboa, Portugal.
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194
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Genetically encoded tools for RNA imaging in living cells. Curr Opin Biotechnol 2015; 31:42-9. [DOI: 10.1016/j.copbio.2014.07.012] [Citation(s) in RCA: 39] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2014] [Accepted: 07/30/2014] [Indexed: 12/11/2022]
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195
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Gaspar I, Ephrussi A. Strength in numbers: quantitative single-molecule RNA detection assays. WILEY INTERDISCIPLINARY REVIEWS-DEVELOPMENTAL BIOLOGY 2015; 4:135-50. [PMID: 25645249 PMCID: PMC5024021 DOI: 10.1002/wdev.170] [Citation(s) in RCA: 43] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 10/09/2014] [Accepted: 12/02/2014] [Indexed: 01/19/2023]
Abstract
Gene expression is a fundamental process that underlies development, homeostasis, and behavior of organisms. The fact that it relies on nucleic acid intermediates, which can specifically interact with complementary probes, provides an excellent opportunity for studying the multiple steps—transcription, RNA processing, transport, translation, degradation, and so forth—through which gene function manifests. Over the past three decades, the toolbox of nucleic acid science has expanded tremendously, making high‐precision in situ detection of DNA and RNA possible. This has revealed that many—probably the vast majority of—transcripts are distributed within the cytoplasm or the nucleus in a nonrandom fashion. With the development of microscopy techniques we have learned not only about the qualitative localization of these molecules but also about their absolute numbers with great precision. Single‐molecule techniques for nucleic acid detection have been transforming our views of biology with elementary power: cells are not average members of their population but are highly distinct individuals with greatly and suddenly changing gene expression, and this behavior of theirs can be measured, modeled, and thus predicted and, finally, comprehended. WIREs Dev Biol 2015, 4:135–150. doi: 10.1002/wdev.170 For further resources related to this article, please visit the
WIREs website. Conflict of interest: The authors have declared no conflicts of interest for this article.
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Affiliation(s)
- Imre Gaspar
- Developmental Biology Unit, European Molecular Biology Laboratory, Heidelberg, Germany
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196
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Corrigan AM, Chubb JR. Quantitative measurement of transcription dynamics in living cells. Methods Cell Biol 2015; 125:29-41. [PMID: 25640422 DOI: 10.1016/bs.mcb.2014.11.001] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
In a wide range of organisms the kinetics of transcription have been found to be noisy, with "bursts" or "pulses" of transcription interspersed with irregular periods of inactivity. The in vivo analysis of transcription dynamics can be most directly monitored using RNA stem loop motifs derived from MS2 and other bacteriophages. Here we describe the implementation of the MS2 RNA detection system and the steps required for precise measurement of transcription dynamics in highly motile cells. Automated image processing techniques are used to track large numbers of cells and measure transcription in a systematic and unbiased manner. We discuss popular methods for automatic image segmentation and frame-to-frame tracking of cells, and the considerations required to make measurements as quantitatively as possible.
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Affiliation(s)
- Adam M Corrigan
- MRC Laboratory for Molecular Cell Biology, University College London, Gower Street, London, WC1E 6BT, United Kingdom
| | - Jonathan R Chubb
- MRC Laboratory for Molecular Cell Biology, University College London, Gower Street, London, WC1E 6BT, United Kingdom
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197
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Spille JH, Kubitscheck U. Labelling and imaging of single endogenous messenger RNA particles in vivo. J Cell Sci 2015; 128:3695-706. [DOI: 10.1242/jcs.166728] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023] Open
Abstract
ABSTRACT
RNA molecules carry out widely diverse functions in numerous different physiological processes in living cells. The RNA life cycle from transcription, through the processing of nascent RNA, to the regulatory function of non-coding RNA and cytoplasmic translation of messenger RNA has been studied extensively using biochemical and molecular biology techniques. In this Commentary, we highlight how single molecule imaging and particle tracking can yield further insight into the dynamics of RNA particles in living cells. In the past few years, a variety of bright and photo-stable labelling techniques have been developed to generate sufficient contrast for imaging of single endogenous RNAs in vivo. New imaging modalities allow determination of not only lateral but also axial positions with high precision within the cellular context, and across a wide range of specimen from yeast and bacteria to cultured cells, and even multicellular organisms or live animals. A whole range of methods to locate and track single particles, and to analyze trajectory data are available to yield detailed information about the kinetics of all parts of the RNA life cycle. Although the concepts presented are applicable to all types of RNA, we showcase here the wealth of information gained from in vivo imaging of single particles by discussing studies investigating dynamics of intranuclear trafficking, nuclear pore transport and cytoplasmic transport of endogenous messenger RNA.
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Affiliation(s)
- Jan-Hendrik Spille
- Institute of Physical and Theoretical Chemistry, Rheinische Friedrich-Wilhelms-University Bonn, Wegeler Str. 12, Bonn 53115, Germany
| | - Ulrich Kubitscheck
- Institute of Physical and Theoretical Chemistry, Rheinische Friedrich-Wilhelms-University Bonn, Wegeler Str. 12, Bonn 53115, Germany
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198
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In the right place at the right time: visualizing and understanding mRNA localization. Nat Rev Mol Cell Biol 2014; 16:95-109. [PMID: 25549890 DOI: 10.1038/nrm3918] [Citation(s) in RCA: 379] [Impact Index Per Article: 37.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
The spatial regulation of protein translation is an efficient way to create functional and structural asymmetries in cells. Recent research has furthered our understanding of how individual cells spatially organize protein synthesis, by applying innovative technology to characterize the relationship between mRNAs and their regulatory proteins, single-mRNA trafficking dynamics, physiological effects of abrogating mRNA localization in vivo and for endogenous mRNA labelling. The implementation of new imaging technologies has yielded valuable information on mRNA localization, for example, by observing single molecules in tissues. The emerging movements and localization patterns of mRNAs in morphologically distinct unicellular organisms and in neurons have illuminated shared and specialized mechanisms of mRNA localization, and this information is complemented by transgenic and biochemical techniques that reveal the biological consequences of mRNA mislocalization.
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199
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Abstract
Analysis of the mechanisms underlying cell fates requires the molecular quantification of cellular features. Classical techniques use population average readouts at single time points. However, these approaches mask cellular heterogeneity and dynamics and are limited for studying rare and heterogeneous cell populations like stem cells. Techniques for single-cell analyses, ideally allowing non-invasive quantification of molecular dynamics and cellular behaviour over time, are required for studying stem cells. Here, we review the development and application of these techniques to stem cell research.
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200
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Lauer FM, Kaemmerer E, Meckel T. Single molecule microscopy in 3D cell cultures and tissues. Adv Drug Deliv Rev 2014; 79-80:79-94. [PMID: 25453259 DOI: 10.1016/j.addr.2014.10.008] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/13/2014] [Revised: 09/20/2014] [Accepted: 10/03/2014] [Indexed: 12/19/2022]
Abstract
From the onset of the first microscopic visualization of single fluorescent molecules in living cells at the beginning of this century, to the present, almost routine application of single molecule microscopy, the method has well-proven its ability to contribute unmatched detailed insight into the heterogeneous and dynamic molecular world life is composed of. Except for investigations on bacteria and yeast, almost the entire story of success is based on studies on adherent mammalian 2D cell cultures. However, despite this continuous progress, the technique was not able to keep pace with the move of the cell biology community to adapt 3D cell culture models for basic research, regenerative medicine, or drug development and screening. In this review, we will summarize the progress, which only recently allowed for the application of single molecule microscopy to 3D cell systems and give an overview of the technical advances that led to it. While initially posing a challenge, we finally conclude that relevant 3D cell models will become an integral part of the on-going success of single molecule microscopy.
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Affiliation(s)
- Florian M Lauer
- Membrane Dynamics, Department of Biology, Technische Universität Darmstadt, Schnittspahnstrasse 3-5, 64287 Darmstadt, Germany
| | - Elke Kaemmerer
- Membrane Dynamics, Department of Biology, Technische Universität Darmstadt, Schnittspahnstrasse 3-5, 64287 Darmstadt, Germany; Institute of Health and Biomedical Innovation, Science and Engineering Faculty, Queensland University of Technology, 60 Musk Ave, Kelvin Grove, 4059 QLD, Brisbane, Australia
| | - Tobias Meckel
- Membrane Dynamics, Department of Biology, Technische Universität Darmstadt, Schnittspahnstrasse 3-5, 64287 Darmstadt, Germany.
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