1
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Nakanishi K. Anatomy of four human Argonaute proteins. Nucleic Acids Res 2022; 50:6618-6638. [PMID: 35736234 PMCID: PMC9262622 DOI: 10.1093/nar/gkac519] [Citation(s) in RCA: 31] [Impact Index Per Article: 15.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2022] [Revised: 05/26/2022] [Accepted: 05/30/2022] [Indexed: 12/24/2022] Open
Abstract
MicroRNAs (miRNAs) bind to complementary target RNAs and regulate their gene expression post-transcriptionally. These non-coding regulatory RNAs become functional after loading into Argonaute (AGO) proteins to form the effector complexes. Humans have four AGO proteins, AGO1, AGO2, AGO3 and AGO4, which share a high sequence identity. Since most miRNAs are found across the four AGOs, it has been thought that they work redundantly, and AGO2 has been heavily studied as the exemplified human paralog. Nevertheless, an increasing number of studies have found that the other paralogs play unique roles in various biological processes and diseases. In the last decade, the structural study of the four AGOs has provided the field with solid structural bases. This review exploits the completed structural catalog to describe common features and differences in target specificity across the four AGOs.
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Affiliation(s)
- Kotaro Nakanishi
- To whom correspondence should be addressed. Tel: +1 614 688 2188;
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2
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Shiohama Y, Fujita R, Sonokawa M, Hisano M, Kotake Y, Krstic-Demonacos M, Demonacos C, Kashiwazaki G, Kitayama T, Fujii M. Elimination of Off-Target Effect by Chemical Modification of 5′-End of Small Interfering RNA. Nucleic Acid Ther 2022; 32:438-447. [DOI: 10.1089/nat.2021.0068] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Affiliation(s)
- Yasuo Shiohama
- Environmental and Biological Information Group, Tropical Biosphere Research Centre, University of the Ryukyus, Nishihara, Japan
| | - Ryosuke Fujita
- Department of Biological & Environmental Chemistry, School of Humanity Oriented Science and Technology, Kindai University, Iizuka, Japan
| | - Maika Sonokawa
- Department of Biological & Environmental Chemistry, School of Humanity Oriented Science and Technology, Kindai University, Iizuka, Japan
| | - Masaaki Hisano
- Department of Biological & Environmental Chemistry, School of Humanity Oriented Science and Technology, Kindai University, Iizuka, Japan
| | - Yojiro Kotake
- Department of Biological & Environmental Chemistry, School of Humanity Oriented Science and Technology, Kindai University, Iizuka, Japan
| | - Marija Krstic-Demonacos
- School of Science, Engineering and Environment, University of Salford, Salford, United Kingdom
| | - Constantinos Demonacos
- Division of Pharmacy and Optometry, Faculty of Biology Medicine and Health, School of Health Science, University of Manchester, Manchester, United Kingdom
| | - Gengo Kashiwazaki
- Department of Advanced Bioscience, Faculty of Agriculture, Kindai University, Nara, Japan
| | - Takashi Kitayama
- Department of Advanced Bioscience, Faculty of Agriculture, Kindai University, Nara, Japan
| | - Masayuki Fujii
- Department of Biological & Environmental Chemistry, School of Humanity Oriented Science and Technology, Kindai University, Iizuka, Japan
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3
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Salim L, Desaulniers JP. To Conjugate or to Package? A Look at Targeted siRNA Delivery Through Folate Receptors. Nucleic Acid Ther 2020; 31:21-38. [PMID: 33121373 DOI: 10.1089/nat.2020.0893] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022] Open
Abstract
RNA interference (RNAi) applications have evolved from experimental tools to study gene function to the development of a novel class of gene-silencing therapeutics. Despite decades of research, it was not until August 2018 that the US FDA approved the first-ever RNAi drug, marking a new era for RNAi therapeutics. Although there are many limitations associated with the inherent structure of RNA, delivery to target cells and tissues remains the most challenging. RNAs are unable to diffuse across cellular membranes due to their large size and polyanionic backbone and, therefore, require a delivery vector. RNAi molecules can be conjugated to a targeting ligand or packaged into a delivery vehicle. Alnylam has used both strategies in their FDA-approved formulations to achieve efficient delivery to the liver. To harness the full potential of RNAi therapeutics, however, we must be able to target additional cells and tissues. One promising target is the folate receptor α, which is overexpressed in a variety of tumors despite having limited expression and distribution in normal tissues. Folate can be conjugated directly to the RNAi molecule or used to functionalize delivery vehicles. In this review, we compare both delivery strategies and discuss the current state of research in the area of folate-mediated delivery of RNAi molecules.
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Affiliation(s)
- Lidya Salim
- Faculty of Science, University of Ontario Institute of Technology, Oshawa, Canada
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4
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Medley JC, Panzade G, Zinovyeva AY. microRNA strand selection: Unwinding the rules. WILEY INTERDISCIPLINARY REVIEWS-RNA 2020; 12:e1627. [PMID: 32954644 PMCID: PMC8047885 DOI: 10.1002/wrna.1627] [Citation(s) in RCA: 89] [Impact Index Per Article: 22.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 06/22/2020] [Revised: 08/18/2020] [Accepted: 08/27/2020] [Indexed: 12/17/2022]
Abstract
microRNAs (miRNAs) play a central role in the regulation of gene expression by targeting specific mRNAs for degradation or translational repression. Each miRNA is post‐transcriptionally processed into a duplex comprising two strands. One of the two miRNA strands is selectively loaded into an Argonaute protein to form the miRNA‐Induced Silencing Complex (miRISC) in a process referred to as miRNA strand selection. The other strand is ejected from the complex and is subject to degradation. The target gene specificity of miRISC is determined by sequence complementarity between the Argonaute‐loaded miRNA strand and target mRNA. Each strand of the miRNA duplex has the capacity to be loaded into miRISC and possesses a unique seed sequence. Therefore, miRNA strand selection plays a defining role in dictating the specificity of miRISC toward its targets and provides a mechanism to alter gene expression in a switch‐like fashion. Aberrant strand selection can lead to altered gene regulation by miRISC and is observed in several human diseases including cancer. Previous and emerging data shape the rules governing miRNA strand selection and shed light on how these rules can be circumvented in various physiological and pathological contexts. This article is categorized under:RNA Processing > Processing of Small RNAs Regulatory RNAs/RNAi/Riboswitches > Regulatory RNAs Regulatory RNAs/RNAi/Riboswitches > Biogenesis of Effector Small RNAs
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Affiliation(s)
- Jeffrey C Medley
- Division of Biology, Kansas State University, Manhattan, Kansas, USA
| | - Ganesh Panzade
- Division of Biology, Kansas State University, Manhattan, Kansas, USA
| | - Anna Y Zinovyeva
- Division of Biology, Kansas State University, Manhattan, Kansas, USA
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5
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Mutual Regulation of RNA Silencing and the IFN Response as an Antiviral Defense System in Mammalian Cells. Int J Mol Sci 2020; 21:ijms21041348. [PMID: 32079277 PMCID: PMC7072894 DOI: 10.3390/ijms21041348] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2019] [Revised: 02/14/2020] [Accepted: 02/15/2020] [Indexed: 12/20/2022] Open
Abstract
RNA silencing is a posttranscriptional gene silencing mechanism directed by endogenous small non-coding RNAs called microRNAs (miRNAs). By contrast, the type-I interferon (IFN) response is an innate immune response induced by exogenous RNAs, such as viral RNAs. Endogenous and exogenous RNAs have typical structural features and are recognized accurately by specific RNA-binding proteins in each pathway. In mammalian cells, both RNA silencing and the IFN response are induced by double-stranded RNAs (dsRNAs) in the cytoplasm, but have long been considered two independent pathways. However, recent reports have shed light on crosstalk between the two pathways, which are mutually regulated by protein–protein interactions triggered by viral infection. This review provides brief overviews of RNA silencing and the IFN response and an outline of the molecular mechanism of their crosstalk and its biological implications. Crosstalk between RNA silencing and the IFN response may reveal a novel antiviral defense system that is regulated by miRNAs in mammalian cells.
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6
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Vocelle D, Chan C, Walton SP. Endocytosis Controls siRNA Efficiency: Implications for siRNA Delivery Vehicle Design and Cell-Specific Targeting. Nucleic Acid Ther 2020; 30:22-32. [PMID: 31718426 PMCID: PMC6987736 DOI: 10.1089/nat.2019.0804] [Citation(s) in RCA: 16] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/12/2019] [Accepted: 10/10/2019] [Indexed: 12/19/2022] Open
Abstract
While small interfering RNAs (siRNAs) are commonly used for laboratory studies, development of siRNA therapeutics has been slower than expected, due, in part, to a still limited understanding of the endocytosis and intracellular trafficking of siRNA-containing complexes. With the recent characterization of multiple clathrin-/caveolin-independent endocytic pathways, that is, those mediated by Graf1, Arf6, and flotillin, it has become clear that the endocytic mechanism influences subsequent intracellular processing of the internalized cargo. To explore siRNA delivery in light of these findings, we developed a novel assay that differentiates uptake by each of the endocytic pathways and can be used to determine whether endocytosis by a pathway leads to the initiation of RNA interference (RNAi). Using Lipofectamine 2000 (LF2K), we determined the endocytosis pathway leading to active silencing (whether by clathrin, caveolin, Arf6, Graf1, flotillin, or macropinocytosis) across multiple cell types (HeLa, H1299, HEK293, and HepG2). We showed that LF2K is internalized by Graf1-, Arf6-, or flotillin-mediated endocytosis for the initiation of RNAi, depending on cell type. In addition, we found that a portion of siRNA-containing complexes is internalized by pathways that do not lead to initiation of silencing. Inhibition of these pathways enhanced intracellular levels of siRNAs with concomitant enhancement of silencing.
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Affiliation(s)
- Daniel Vocelle
- Department of Chemical Engineering and Materials Science, Michigan State University, East Lansing, Michigan
| | - Christina Chan
- Department of Chemical Engineering and Materials Science, Michigan State University, East Lansing, Michigan
- Department of Biochemistry and Molecular Biology, Michigan State University, East Lansing, Michigan
| | - S. Patrick Walton
- Department of Chemical Engineering and Materials Science, Michigan State University, East Lansing, Michigan
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7
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Masliah G, Maris C, König SL, Yulikov M, Aeschimann F, Malinowska AL, Mabille J, Weiler J, Holla A, Hunziker J, Meisner-Kober N, Schuler B, Jeschke G, Allain FHT. Structural basis of siRNA recognition by TRBP double-stranded RNA binding domains. EMBO J 2018; 37:embj.201797089. [PMID: 29449323 PMCID: PMC5852647 DOI: 10.15252/embj.201797089] [Citation(s) in RCA: 38] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2017] [Revised: 01/10/2018] [Accepted: 01/12/2018] [Indexed: 11/23/2022] Open
Abstract
The accurate cleavage of pre‐micro(mi)RNAs by Dicer and mi/siRNA guide strand selection are important steps in forming the RNA‐induced silencing complex (RISC). The role of Dicer binding partner TRBP in these processes remains poorly understood. Here, we solved the solution structure of the two N‐terminal dsRNA binding domains (dsRBDs) of TRBP in complex with a functionally asymmetric siRNA using NMR, EPR, and single‐molecule spectroscopy. We find that siRNA recognition by the dsRBDs is not sequence‐specific but rather depends on the RNA shape. The two dsRBDs can swap their binding sites, giving rise to two equally populated, pseudo‐symmetrical complexes, showing that TRBP is not a primary sensor of siRNA asymmetry. Using our structure to model a Dicer‐TRBP‐siRNA ternary complex, we show that TRBP's dsRBDs and Dicer's RNase III domains bind a canonical 19 base pair siRNA on opposite sides, supporting a mechanism whereby TRBP influences Dicer‐mediated cleavage accuracy by binding the dsRNA region of the pre‐miRNA during Dicer cleavage.
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Affiliation(s)
- Gregoire Masliah
- Institute of Molecular Biology and Biophysics, ETH Zürich, Zürich, Switzerland
| | - Christophe Maris
- Institute of Molecular Biology and Biophysics, ETH Zürich, Zürich, Switzerland
| | | | - Maxim Yulikov
- Laboratory of Physical Chemistry, ETH Zürich, Zürich, Switzerland
| | | | - Anna L Malinowska
- Institute of Pharmaceutical Sciences, Department of Chemistry and Applied Biosciences, ETH Zürich, Zürich, Switzerland
| | - Julie Mabille
- Novartis Institutes for Biomedical Research, Basel, Switzerland
| | - Jan Weiler
- Novartis Institutes for Biomedical Research, Basel, Switzerland
| | - Andrea Holla
- Department of Biochemistry, University of Zürich, Zürich, Switzerland
| | - Juerg Hunziker
- Novartis Institutes for Biomedical Research, Basel, Switzerland
| | | | - Benjamin Schuler
- Department of Biochemistry, University of Zürich, Zürich, Switzerland
| | - Gunnar Jeschke
- Laboratory of Physical Chemistry, ETH Zürich, Zürich, Switzerland
| | - Frederic H-T Allain
- Institute of Molecular Biology and Biophysics, ETH Zürich, Zürich, Switzerland
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8
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Tants JN, Fesser S, Kern T, Stehle R, Geerlof A, Wunderlich C, Juen M, Hartlmüller C, Böttcher R, Kunzelmann S, Lange O, Kreutz C, Förstemann K, Sattler M. Molecular basis for asymmetry sensing of siRNAs by the Drosophila Loqs-PD/Dcr-2 complex in RNA interference. Nucleic Acids Res 2017; 45:12536-12550. [PMID: 29040648 PMCID: PMC5716069 DOI: 10.1093/nar/gkx886] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2017] [Revised: 09/22/2017] [Accepted: 09/22/2017] [Indexed: 12/26/2022] Open
Abstract
RNA interference defends against RNA viruses and retro-elements within an organism's genome. It is triggered by duplex siRNAs, of which one strand is selected to confer sequence-specificity to the RNA induced silencing complex (RISC). In Drosophila, Dicer-2 (Dcr-2) and the double-stranded RNA binding domain (dsRBD) protein R2D2 form the RISC loading complex (RLC) and select one strand of exogenous siRNAs according to the relative thermodynamic stability of base-pairing at either end. Through genome editing we demonstrate that Loqs-PD, the Drosophila homolog of human TAR RNA binding protein (TRBP) and a paralog of R2D2, forms an alternative RLC with Dcr-2 that is required for strand choice of endogenous siRNAs in S2 cells. Two canonical dsRBDs in Loqs-PD bind to siRNAs with enhanced affinity compared to miRNA/miRNA* duplexes. Structural analysis, NMR and biophysical experiments indicate that the Loqs-PD dsRBDs can slide along the RNA duplex to the ends of the siRNA. A moderate but notable binding preference for the thermodynamically more stable siRNA end by Loqs-PD alone is greatly amplified in complex with Dcr-2 to initiate strand discrimination by asymmetry sensing in the RLC.
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Affiliation(s)
- Jan-Niklas Tants
- Institute of Structural Biology, Helmholtz Zentrum München, 85764 Neuherberg, Germany
- Center for Integrated Protein Science Munich at Chair of Biomolecular NMR Spectroscopy, Department Chemie, Technische Universität München, 85748 Garching, Germany
| | - Stephanie Fesser
- Genzentrum & Department Biochemie, Ludwig-Maximilians-Universität, 81377 München, Germany
| | - Thomas Kern
- Institute of Structural Biology, Helmholtz Zentrum München, 85764 Neuherberg, Germany
- Center for Integrated Protein Science Munich at Chair of Biomolecular NMR Spectroscopy, Department Chemie, Technische Universität München, 85748 Garching, Germany
| | - Ralf Stehle
- Institute of Structural Biology, Helmholtz Zentrum München, 85764 Neuherberg, Germany
- Center for Integrated Protein Science Munich at Chair of Biomolecular NMR Spectroscopy, Department Chemie, Technische Universität München, 85748 Garching, Germany
| | - Arie Geerlof
- Institute of Structural Biology, Helmholtz Zentrum München, 85764 Neuherberg, Germany
| | - Christoph Wunderlich
- Institute of Organic Chemistry and Center for Molecular Biosciences CMBI, Universität Innsbruck, 6020 Innsbruck, Austria
| | - Michael Juen
- Institute of Organic Chemistry and Center for Molecular Biosciences CMBI, Universität Innsbruck, 6020 Innsbruck, Austria
| | - Christoph Hartlmüller
- Institute of Structural Biology, Helmholtz Zentrum München, 85764 Neuherberg, Germany
- Center for Integrated Protein Science Munich at Chair of Biomolecular NMR Spectroscopy, Department Chemie, Technische Universität München, 85748 Garching, Germany
| | - Romy Böttcher
- Genzentrum & Department Biochemie, Ludwig-Maximilians-Universität, 81377 München, Germany
| | - Stefan Kunzelmann
- Genzentrum & Department Biochemie, Ludwig-Maximilians-Universität, 81377 München, Germany
| | - Oliver Lange
- Center for Integrated Protein Science Munich at Chair of Biomolecular NMR Spectroscopy, Department Chemie, Technische Universität München, 85748 Garching, Germany
| | - Christoph Kreutz
- Institute of Organic Chemistry and Center for Molecular Biosciences CMBI, Universität Innsbruck, 6020 Innsbruck, Austria
| | - Klaus Förstemann
- Genzentrum & Department Biochemie, Ludwig-Maximilians-Universität, 81377 München, Germany
| | - Michael Sattler
- Institute of Structural Biology, Helmholtz Zentrum München, 85764 Neuherberg, Germany
- Center for Integrated Protein Science Munich at Chair of Biomolecular NMR Spectroscopy, Department Chemie, Technische Universität München, 85748 Garching, Germany
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9
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Abstract
Although the antiviral kinase PKR was originally characterized as a double-stranded RNA activated enzyme it can be stimulated by RNAs containing limited secondary structure. Single-stranded regions in such RNAs contribute to binding and activation but the mechanism is not understood. Here, we demonstrate that single-stranded RNAs bind to PKR with micromolar dissociation constants and can induce activation. Addition of a 5'-triphosphate slightly enhances binding affinity. Single-stranded RNAs also activate PKR constructs lacking the double-stranded RNA binding domain and bind to a basic region adjacent to the N-terminus of the kinase. However, the isolated kinase is not activated by and does not bind single-stranded RNA. Photocrosslinking measurements demonstrate that that the basic region interacts with RNA in the context of full length PKR. We propose that bivalent interactions with the double stranded RNA binding domain and the basic region underlie the ability of RNAs containing limited structure to activate PKR by enhancing binding affinity and thereby increasing the population of productive complexes containing two PKRs bound to a single RNA.
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10
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Paces J, Nic M, Novotny T, Svoboda P. Literature review of baseline information to support the risk assessment of RNAi‐based GM plants. ACTA ACUST UNITED AC 2017. [PMCID: PMC7163844 DOI: 10.2903/sp.efsa.2017.en-1246] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Affiliation(s)
- Jan Paces
- Institute of Molecular Genetics of the Academy of Sciences of the Czech Republic (IMG)
| | | | | | - Petr Svoboda
- Institute of Molecular Genetics of the Academy of Sciences of the Czech Republic (IMG)
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11
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Angart PA, Carlson RJ, Adu-Berchie K, Walton SP. Terminal Duplex Stability and Nucleotide Identity Differentially Control siRNA Loading and Activity in RNA Interference. Nucleic Acid Ther 2016; 26:309-317. [PMID: 27399870 PMCID: PMC5067871 DOI: 10.1089/nat.2016.0612] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2016] [Accepted: 05/06/2016] [Indexed: 01/17/2023] Open
Abstract
Efficient short interfering RNA (siRNA)-mediated gene silencing requires selection of a sequence that is complementary to the intended target and possesses sequence and structural features that encourage favorable functional interactions with the RNA interference (RNAi) pathway proteins. In this study, we investigated how terminal sequence and structural characteristics of siRNAs contribute to siRNA strand loading and silencing activity and how these characteristics ultimately result in a functionally asymmetric duplex in cultured HeLa cells. Our results reiterate that the most important characteristic in determining siRNA activity is the 5' terminal nucleotide identity. Our findings further suggest that siRNA loading is controlled principally by the hybridization stability of the 5' terminus (Nucleotides: 1-2) of each siRNA strand, independent of the opposing terminus. Postloading, RNA-induced silencing complex (RISC)-specific activity was found to be improved by lower hybridization stability in the 5' terminus (Nucleotides: 3-4) of the loaded siRNA strand and greater hybridization stability toward the 3' terminus (Nucleotides: 17-18). Concomitantly, specific recognition of the 5' terminal nucleotide sequence by human Argonaute 2 (Ago2) improves RISC half-life. These findings indicate that careful selection of siRNA sequences can maximize both the loading and the specific activity of the intended guide strand.
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Affiliation(s)
- Phillip A Angart
- Department of Chemical Engineering and Materials Science, Michigan State University , East Lansing, Michigan
| | - Rebecca J Carlson
- Department of Chemical Engineering and Materials Science, Michigan State University , East Lansing, Michigan
| | - Kwasi Adu-Berchie
- Department of Chemical Engineering and Materials Science, Michigan State University , East Lansing, Michigan
| | - S Patrick Walton
- Department of Chemical Engineering and Materials Science, Michigan State University , East Lansing, Michigan
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12
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Vocelle D, Chesniak OM, Malefyt AP, Comiskey G, Adu-Berchie K, Smith MR, Chan C, Walton SP. Dextran functionalization enhances nanoparticle-mediated siRNA delivery and silencing. TECHNOLOGY 2016; 4:42. [PMID: 27774502 PMCID: PMC5072529 DOI: 10.1142/s2339547816400100] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/16/2023]
Abstract
Understanding the endocytosis and intracellular trafficking of short interfering RNA (siRNA) delivery vehicle complexes remains a critical bottleneck in designing siRNA delivery vehicles for highly active RNA interference (RNAi)-based therapeutics. In this study, we show that dextran functionalization of silica nanoparticles enhanced uptake and intracellular delivery of siRNAs in cultured cells. Using pharmacological inhibitors for endocytotic pathways, we determined that our complexes are endocytosed via a previously unreported mechanism for siRNA delivery in which dextran initiates scavenger receptor-mediated endocytosis through a clathrin/caveolin-independent process. Our findings suggest that siRNA delivery efficiency could be enhanced by incorporating dextran into existing delivery platforms to activate scavenger receptor activity across a variety of target cell types.
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Affiliation(s)
- Daniel Vocelle
- Department of Chemical Engineering and Materials Science, Michigan State University, East Lansing, MI 48824-1226, USA
| | - Olivia M Chesniak
- Department of Chemistry, Michigan State University, East Lansing, MI 48824-1226, USA
| | - Amanda P Malefyt
- Department of Chemical Engineering and Materials Science, Michigan State University, East Lansing, MI 48824-1226, USA
| | - Georgina Comiskey
- Department of Chemistry, Michigan State University, East Lansing, MI 48824-1226, USA
| | - Kwasi Adu-Berchie
- Department of Chemical Engineering and Materials Science, Michigan State University, East Lansing, MI 48824-1226, USA
| | - Milton R Smith
- Department of Chemistry, Michigan State University, East Lansing, MI 48824-1226, USA
| | - Christina Chan
- Department of Chemical Engineering and Materials Science, Michigan State University, East Lansing, MI 48824-1226, USA; Department of Biochemistry and Molecular Biology, Michigan State University, East Lansing, MI 48824-1226, USA
| | - S Patrick Walton
- Department of Chemical Engineering and Materials Science, Michigan State University, East Lansing, MI 48824-1226, USA
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13
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Recombinant hTRBP and hPACT Modulate hAgo2-Catalyzed siRNA-Mediated Target RNA Cleavage In Vitro. PLoS One 2016; 11:e0146814. [PMID: 26784517 PMCID: PMC4718636 DOI: 10.1371/journal.pone.0146814] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/16/2015] [Accepted: 12/21/2015] [Indexed: 11/19/2022] Open
Abstract
The human TAR RNA-binding protein (hTRBP) and protein activator of protein kinase R (hPACT) are important players in RNA interference (RNAi). Together with hArgonaute2 (hAgo2) and hDicer they have been reported to form the RISC-loading complex (RLC). Among other functions, hTRBP was suggested to assist the loading of hAgo2 with small interfering RNAs (siRNAs) within the RLC. Although several studies have been conducted to evaluate the specific functions of hTRBP and hPACT in RNAi, exact mechanisms and modes of action are still unknown. Here, we present a biochemical study further evaluating the role of hTRBP and hPACT in hAgo2-loading. We found that both proteins enhance hAgo2-mediated RNA cleavage significantly; even a hAgo2 mutant impaired in siRNA binding shows full cleavage activity in the presence of hTRBP or hPACT. Pre-steady state binding studies reveal that the assembly of wildtype-hAgo2 (wt-hAgo2) and siRNAs remains largely unaffected, whereas the binding of mutant hAgo2-PAZ9 to siRNA is restored by adding either hTRBP or hPACT. We conclude that both proteins assist in positioning the siRNA within hAgo2 to ensure optimal binding and cleavage. Overall, our data indicate that hTRBP and hPACT are part of a regulative system of RNAi that is important for efficient target RNA cleavage.
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14
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Daniels SM, Sinck L, Ward NJ, Melendez-Peña CE, Scarborough RJ, Azar I, Rance E, Daher A, Pang KM, Rossi JJ, Gatignol A. HIV-1 RRE RNA acts as an RNA silencing suppressor by competing with TRBP-bound siRNAs. RNA Biol 2015; 12:123-35. [PMID: 25668122 DOI: 10.1080/15476286.2015.1014759] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022] Open
Abstract
Several proteins and RNAs expressed by mammalian viruses have been reported to interfere with RNA interference (RNAi) activity. We investigated the ability of the HIV-1-encoded RNA elements Trans-Activation Response (TAR) and Rev-Response Element (RRE) to alter RNAi. MicroRNA let7-based assays showed that RRE is a potent suppressor of RNAi activity, while TAR displayed moderate RNAi suppression. We demonstrate that RRE binds to TAR-RNA Binding Protein (TRBP), an essential component of the RNA Induced Silencing Complex (RISC). The binding of TAR and RRE to TRBP displaces small interfering (si)RNAs from binding to TRBP. Several stem-deleted RRE mutants lost their ability to suppress RNAi activity, which correlated with a reduced ability to compete with siRNA-TRBP binding. A lentiviral vector expressing TAR and RRE restricted RNAi, but RNAi was restored when Rev or GagPol were coexpressed. Adenoviruses are restricted by RNAi and encode their own suppressors of RNAi, the Virus-Associated (VA) RNA elements. RRE enhanced the replication of wild-type and VA-deficient adenovirus. Our work describes RRE as a novel suppressor of RNAi that acts by competing with siRNAs rather than by disrupting the RISC. This function is masked in lentiviral vectors co-expressed with viral proteins and thus will not affect their use in gene therapy. The potent RNAi suppressive effects of RRE identified in this study could be used to enhance the expression of RNAi restricted viruses used in oncolysis such as adenoviruses.
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Key Words
- Ago2, Argonaute-2
- EGFP, enhanced green fluorescent protein
- EMSA, electrophoresis mobility shift assay
- FL, firefly luciferase
- GAPDH, glyceraldehyde-3-phosphate dehydrogenase
- HIV, human immunodeficiency virus
- HIV-1
- IP, immunoprecipitation
- NC, nucleocapsid
- PAGE, polyacrylamide gel electrophoresis
- RISC, RNA-Induced Silencing Complex
- RL, Renilla luciferase
- RNA interference
- RNA silencing suppressor
- RNAi, RNA interference
- RRE, Rev Response Element
- RSS, RNA silencing suppressor
- RT, reverse transcription
- Rev-Response Element RNA
- TAR RNA Binding Protein (TRBP)
- TAR, trans-activation responsive element
- TRBP, TAR RNA Binding Protein
- Trans-Activation Response Element
- UTR, untranslated region
- VA, virus-associated
- WT, wild-type
- adenovirus
- ds, double-stranded
- lentiviral vectors
- miRNA, micro RNA
- pre-miRNA, precursor miRNA
- siRNA, small interfering RNA
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Affiliation(s)
- Sylvanne M Daniels
- a Virus-Cell Interactions Laboratory ; Lady Davis Institute for Medical Research ; Montréal , Québec , Canada
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15
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Suzuki HI, Katsura A, Yasuda T, Ueno T, Mano H, Sugimoto K, Miyazono K. Small-RNA asymmetry is directly driven by mammalian Argonautes. Nat Struct Mol Biol 2015; 22:512-21. [PMID: 26098316 DOI: 10.1038/nsmb.3050] [Citation(s) in RCA: 63] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2015] [Accepted: 05/26/2015] [Indexed: 12/17/2022]
Abstract
Asymmetric selection of single-stranded guide RNAs from double-stranded RNA precursors is crucial in RNA silencing-mediated gene regulation. However, the precise mechanisms of small-RNA asymmetry are unclear, especially because asymmetric selection can still occur when the putative asymmetry sensors Drosophila R2D2 and mammalian Dicer are depleted. Here we report a direct contribution of mammalian Argonaute 2 (Ago2) to microRNA (miRNA) asymmetry. Ago2 selects strands with 5'-uridine or 5'-adenosine and thermodynamically unstable 5' ends in parallel through its two sensor regions, which contact the 5' nucleobases and 5'-phosphates of prospective guide strands. Hence, miRNA asymmetry shows superposed patterns reflecting 5'-end nucleotide identity ('digital' pattern) and thermodynamic stability ('analog' pattern). Furthermore, we demonstrate that cancer-associated miRNA variations reprogram asymmetric selection. Finally, our study presents a model of this universal principle, to aid in comprehensive understanding of miRNA function and development of new RNA-silencing therapies in precision medicine.
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Affiliation(s)
- Hiroshi I Suzuki
- 1] David H. Koch Institute for Integrative Cancer Research, Massachusetts Institute of Technology, Cambridge, Massachusetts, USA. [2] Department of Molecular Pathology, Graduate School of Medicine, The University of Tokyo, Tokyo, Japan
| | - Akihiro Katsura
- Department of Molecular Pathology, Graduate School of Medicine, The University of Tokyo, Tokyo, Japan
| | - Takahiko Yasuda
- Department of Cellular Signaling, Graduate School of Medicine, The University of Tokyo, Tokyo, Japan
| | - Toshihide Ueno
- Department of Cellular Signaling, Graduate School of Medicine, The University of Tokyo, Tokyo, Japan
| | - Hiroyuki Mano
- Department of Cellular Signaling, Graduate School of Medicine, The University of Tokyo, Tokyo, Japan
| | - Koichi Sugimoto
- Department of Hematology and Oncology, JR Tokyo General Hospital, Tokyo, Japan
| | - Kohei Miyazono
- Department of Molecular Pathology, Graduate School of Medicine, The University of Tokyo, Tokyo, Japan
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16
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Heyam A, Lagos D, Plevin M. Dissecting the roles of TRBP and PACT in double-stranded RNA recognition and processing of noncoding RNAs. WILEY INTERDISCIPLINARY REVIEWS. RNA 2015; 6:271-89. [PMID: 25630541 PMCID: PMC7169789 DOI: 10.1002/wrna.1272] [Citation(s) in RCA: 32] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 08/07/2014] [Revised: 10/08/2014] [Accepted: 10/09/2014] [Indexed: 12/27/2022]
Abstract
HIV TAR RNA-binding protein (TRBP) and Protein Activator of PKR (PACT) are double-stranded (ds) RNA-binding proteins that participate in both small regulatory RNA biogenesis and the response to viral dsRNA. Despite considerable progress toward understanding the structure-function relationship of TRBP and PACT, their specific roles in these seemingly distinct cellular pathways remain unclear. Both proteins are composed of three copies of the double-stranded RNA-binding domain, two of which interact with dsRNA, while the C-terminal copy mediates protein-protein interactions. PACT and TRBP are found in a complex with the endonuclease Dicer and facilitate processing of immature microRNAs. Their precise contribution to the Dicing step has not yet been defined: possibilities include precursor recruitment, rearrangement of dsRNA within the complex, loading the processed microRNA into the RNA-induced silencing complex, and distinguishing different classes of small dsRNA. TRBP and PACT also interact with the viral dsRNA sensors retinoic acid-inducible gene I (RIG-I) and double-stranded RNA-activated protein kinase (PKR). Current models suggest that PACT enables RIG-I to detect a wider range of viral dsRNAs, while TRBP and PACT exert opposing regulatory effects on PKR. Here, the evidence that implicates TRBP and PACT in regulatory RNA processing and viral dsRNA sensing is reviewed and discussed in the context of their molecular structure. The broader implications of a link between microRNA biogenesis and the innate antiviral response pathway are also considered.
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MESH Headings
- Amino Acid Sequence
- Carboxypeptidases/chemistry
- Carboxypeptidases/metabolism
- Carboxypeptidases/physiology
- Models, Genetic
- Models, Molecular
- Molecular Sequence Data
- Protein Structure, Tertiary
- RNA, Double-Stranded/chemistry
- RNA, Double-Stranded/immunology
- RNA, Double-Stranded/metabolism
- RNA, Untranslated/metabolism
- RNA, Viral/chemistry
- RNA, Viral/immunology
- RNA, Viral/metabolism
- RNA-Binding Proteins/chemistry
- RNA-Binding Proteins/metabolism
- RNA-Binding Proteins/physiology
- Ribonuclease III/chemistry
- Ribonuclease III/metabolism
- Ribonuclease III/physiology
- Structure-Activity Relationship
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Affiliation(s)
- Alex Heyam
- Department of Biology, University of York, York, UK
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17
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Wei J, Ouyang Y, Li X, Zhu B, Yang J, Cui Y, Chen X, Lin F, Long M, Yang A, Dong K, Zhang H. Early growth response gene 1, a TRBP binding protein, is involved in miRNA activity of miR-125a-3p in human cells. Cell Signal 2015; 27:1120-8. [PMID: 25725290 DOI: 10.1016/j.cellsig.2015.02.016] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2014] [Revised: 01/28/2015] [Accepted: 02/16/2015] [Indexed: 11/30/2022]
Abstract
BACKGROUND MicroRNAs (miRNAs) are key regulators of many cellular pathways. However, the picture for components or regulators involved in the process of miRNA biogenesis and function remains to be further elucidated. Early growth response gene 1 (Egr1) has long been considered as tumor suppressor and transcriptional factor involved in cell proliferation and regulation of apoptosis. RESULTS Here we show that Egr1 is able to modulate guide strand loading of certain miRNAs or siRNAs in human HEK293 and A549 cells, which is related with thermodynamic parameters of miRNA or siRNA. Further, we found that Egr1 modulates the silencing activity of miR-125a-3p in vivo. Immunoprecipitation experiment demonstrated that Egr1 could bind miRNA biogenesis protein TAR RNA-binding protein2 (TRBP2), and knockdown TRBP by RNAi abolished the regulating effects of Egr1 on miR-125a-3p efficiency. Further experiments revealed that deleting sequence 97-227aa containing dsRBD B domain of TRBP eliminated the binding phenomenon between Egr1 and TRBP and impaired the effect of Egr1 on miR-125a-3p efficiency. CONCLUSIONS Taken together, our study has demonstrated that Egr1 is able to regulate miRNA activity of miR-125a-3p in human cells through binding TRBP, which highlights an unexpected function of Egr1 in miRNA pathway.
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Affiliation(s)
- Junxia Wei
- Department of Clinical Laboratory and Research Center, Tangdu Hospital, Fourth Military Medical University, Xi'an, China
| | - Yongri Ouyang
- Department of Clinical Laboratory and Research Center, Tangdu Hospital, Fourth Military Medical University, Xi'an, China
| | - Xia Li
- Department of Biochemistry and Molecular Biology, Fourth Military Medical University, Xi'an, China
| | - Baoyi Zhu
- Department of Ophthalmology, Tangdu Hospital, Fourth Military Medical University, Xi'an, China
| | - Jie Yang
- Department of Nephroloogy, Tangdu Hospital, The Fourth Military Medical University, Xi'an, China
| | - Ying Cui
- Department of Clinical Laboratory and Research Center, Tangdu Hospital, Fourth Military Medical University, Xi'an, China
| | - Xi Chen
- Department of Clinical Laboratory and Research Center, Tangdu Hospital, Fourth Military Medical University, Xi'an, China
| | - Fang Lin
- Department of Clinical Laboratory and Research Center, Tangdu Hospital, Fourth Military Medical University, Xi'an, China
| | - Min Long
- Department of Clinical Laboratory and Research Center, Tangdu Hospital, Fourth Military Medical University, Xi'an, China
| | - Angang Yang
- Department of Biochemistry and Molecular Biology, Fourth Military Medical University, Xi'an, China
| | - Ke Dong
- Department of Clinical Laboratory and Research Center, Tangdu Hospital, Fourth Military Medical University, Xi'an, China.
| | - Huizhong Zhang
- Department of Clinical Laboratory and Research Center, Tangdu Hospital, Fourth Military Medical University, Xi'an, China
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18
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Acevedo R, Orench-Rivera N, Quarles KA, Showalter SA. Helical defects in microRNA influence protein binding by TAR RNA binding protein. PLoS One 2015; 10:e0116749. [PMID: 25608000 PMCID: PMC4301919 DOI: 10.1371/journal.pone.0116749] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/18/2014] [Accepted: 12/12/2014] [Indexed: 01/19/2023] Open
Abstract
Background MicroRNAs (miRNAs) are critical post-transcriptional regulators of gene expression. Their precursors have a globally A-form helical geometry, which prevents most proteins from identifying their nucleotide sequence. This suggests the hypothesis that local structural features (e.g., bulges, internal loops) play a central role in specific double-stranded RNA (dsRNA) selection from cellular RNA pools by dsRNA binding domain (dsRBD) containing proteins. Furthermore, the processing enzymes in the miRNA maturation pathway require tandem-dsRBD cofactor proteins for optimal function, suggesting that dsRBDs play a key role in the molecular mechanism for precise positioning of the RNA within these multi-protein complexes. Here, we focus on the tandem-dsRBDs of TRBP, which have been shown to bind dsRNA tightly. Methodology/Principal Findings We present a combination of dsRNA binding assays demonstrating that TRBP binds dsRNA in an RNA-length dependent manner. Moreover, circular dichroism data shows that the number of dsRBD moieties bound to RNA at saturation is different for a tandem-dsRBD construct than for constructs with only one dsRBD per polypeptide, revealing another reason for the selective pressure to maintain multiple domains within a polypeptide chain. Finally, we show that helical defects in precursor miRNA alter the apparent dsRNA size, demonstrating that imperfections in RNA structure influence the strength of TRBP binding. Conclusion/Significance We conclude that TRBP is responsible for recognizing structural imperfections in miRNA precursors, in the sense that TRBP is unable to bind imperfections efficiently and thus is positioned around them. We propose that once positioned around structural defects, TRBP assists Dicer and the rest of the RNA-induced silencing complex (RISC) in providing efficient and homogenous conversion of substrate precursor miRNA into mature miRNA downstream.
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Affiliation(s)
- Roderico Acevedo
- Department of Chemistry and Center for RNA Molecular Biology, The Pennsylvania State University, University Park, Pennsylvania, United States of America
| | - Nichole Orench-Rivera
- Department of Chemistry and Center for RNA Molecular Biology, The Pennsylvania State University, University Park, Pennsylvania, United States of America
| | - Kaycee A. Quarles
- Department of Chemistry and Center for RNA Molecular Biology, The Pennsylvania State University, University Park, Pennsylvania, United States of America
| | - Scott A. Showalter
- Department of Chemistry and Center for RNA Molecular Biology, The Pennsylvania State University, University Park, Pennsylvania, United States of America
- * E-mail:
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19
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Zhang Q, Ichimaru N, Higuchi S, Cai S, Hou J, Fujino M, Nonomura N, Kobayashi M, Ando H, Uno A, Sakurai K, Mochizuki S, Adachi Y, Ohno N, Zou H, Xu J, Li XK, Takahara S. Permanent acceptance of mouse cardiac allografts with CD40 siRNA to induce regulatory myeloid cells by use of a novel polysaccharide siRNA delivery system. Gene Ther 2015; 22:217-26. [DOI: 10.1038/gt.2014.119] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/10/2014] [Revised: 11/06/2014] [Accepted: 11/17/2014] [Indexed: 01/27/2023]
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20
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Li T, Wu M, Zhu YY, Chen J, Chen L. Development of RNA Interference–Based Therapeutics and Application of Multi-Target Small Interfering RNAs. Nucleic Acid Ther 2014; 24:302-12. [DOI: 10.1089/nat.2014.0480] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Affiliation(s)
- Tiejun Li
- Department of Pathological Anatomy, Nantong University, Nantong, China
- Small RNA Technology and Application Institute, Nantong University, Nantong, China
- Department of Life Science Center, Biomics Biotechnologies Co., Ltd., Nantong, China
| | - Meihua Wu
- Department of Pathological Anatomy, Nantong University, Nantong, China
- Small RNA Technology and Application Institute, Nantong University, Nantong, China
- Department of Life Science Center, Biomics Biotechnologies Co., Ltd., Nantong, China
| | - York Yuanyuan Zhu
- Small RNA Technology and Application Institute, Nantong University, Nantong, China
- Department of Life Science Center, Biomics Biotechnologies Co., Ltd., Nantong, China
| | - Jianxin Chen
- Small RNA Technology and Application Institute, Nantong University, Nantong, China
- Department of Life Science Center, Biomics Biotechnologies Co., Ltd., Nantong, China
| | - Li Chen
- Department of Pathological Anatomy, Nantong University, Nantong, China
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21
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Burugu S, Daher A, Meurs EF, Gatignol A. HIV-1 translation and its regulation by cellular factors PKR and PACT. Virus Res 2014; 193:65-77. [PMID: 25064266 DOI: 10.1016/j.virusres.2014.07.014] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2014] [Revised: 07/13/2014] [Accepted: 07/14/2014] [Indexed: 12/24/2022]
Abstract
The synthesis of proteins from viral mRNA is the first step towards viral assembly. Viruses are dependent upon the cellular translation machinery to synthesize their own proteins. The synthesis of proteins from the human immunodeficiency virus (HIV) type 1 and 2 RNAs utilize several alternative mechanisms. The regulation of viral protein production requires a constant interplay between viral requirements and the cell response to viral infection. Among the antiviral cell responses, the interferon-induced RNA activated protein kinase, PKR, regulates the cellular and viral translation. During HIV-1 infection, PKR activation is highly regulated by viral and cellular factors. The cellular TAR RNA Binding Protein, TRBP, the Adenosine Deaminase acting on RNA, ADAR1, and the PKR Activator, PACT, play important roles. Recent data show that PACT changes its function from activator to inhibitor in HIV-1 infected cells. Therefore, HIV-1 has evolved to replicate in cells in which TRBP, ADAR1 and PACT prevent PKR activation to allow efficient viral protein synthesis. This proper translation will initiate the assembly of viral particles.
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Affiliation(s)
- Samantha Burugu
- Virus-cell Interactions Laboratory, Lady Davis Institute for Medical Research, Montréal, QC, Canada; Department of Microbiology and Immunology, McGill University, Montréal, QC, Canada
| | - Aïcha Daher
- Virus-cell Interactions Laboratory, Lady Davis Institute for Medical Research, Montréal, QC, Canada
| | - Eliane F Meurs
- Institut Pasteur, Department of Virology, Hepacivirus and Innate Immunity Unit, Paris, France
| | - Anne Gatignol
- Virus-cell Interactions Laboratory, Lady Davis Institute for Medical Research, Montréal, QC, Canada; Department of Microbiology and Immunology, McGill University, Montréal, QC, Canada; Department of Medicine, Division of Experimental Medicine, McGill University, Montréal, QC, Canada.
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22
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Abstract
MicroRNAs (miRNAs) are small non-coding RNAs that function as guide molecules in RNA silencing. Targeting most protein-coding transcripts, miRNAs are involved in nearly all developmental and pathological processes in animals. The biogenesis of miRNAs is under tight temporal and spatial control, and their dysregulation is associated with many human diseases, particularly cancer. In animals, miRNAs are ∼22 nucleotides in length, and they are produced by two RNase III proteins--Drosha and Dicer. miRNA biogenesis is regulated at multiple levels, including at the level of miRNA transcription; its processing by Drosha and Dicer in the nucleus and cytoplasm, respectively; its modification by RNA editing, RNA methylation, uridylation and adenylation; Argonaute loading; and RNA decay. Non-canonical pathways for miRNA biogenesis, including those that are independent of Drosha or Dicer, are also emerging.
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23
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Vuković L, Koh HR, Myong S, Schulten K. Substrate recognition and specificity of double-stranded RNA binding proteins. Biochemistry 2014; 53:3457-66. [PMID: 24801449 PMCID: PMC4051425 DOI: 10.1021/bi500352s] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
![]()
Recognition of double-stranded (ds)
RNA is an important part of many cellular pathways, including RNA
silencing, viral recognition, RNA editing, processing, and transport.
dsRNA recognition is often achieved by dsRNA binding domains (dsRBDs).
We use atomistic molecular dynamics simulations to examine the binding
interface of the transactivation response RNA binding protein (TRBP)
dsRBDs to dsRNA substrates. Our results explain the exclusive selectivity
of dsRBDs toward dsRNA and against DNA–RNA hybrid and dsDNA
duplexes. We also provide corresponding experimental evidence. The
dsRNA duplex is recognized by dsRBDs through the A-form of three duplex
grooves and by the chemical properties of RNA bases, which have 2′-hydroxyl
groups on their sugar rings. Our simulations show that TRBP dsRBD
discriminates dsRNA- from DNA-containing duplexes primarily through
interactions at two duplex grooves. The simulations also reveal that
the conformation of the DNA–RNA duplex can be altered by dsRBD
proteins, resulting in a weak binding of dsRBDs to DNA–RNA
hybrids. Our study reveals the structural and molecular basis of protein–RNA
interaction that gives rise to the observed substrate specificity
of dsRNA binding proteins.
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Affiliation(s)
- Lela Vuković
- Department of Physics, University of Illinois at Urbana-Champaign , Urbana, Illinois 61801, United States
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24
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Ida H, Fukuda K, Tachibana A, Tanabe T. Long DNA passenger strand highly improves the activity of RNA/DNA hybrid siRNAs. J Biosci Bioeng 2014; 117:401-6. [DOI: 10.1016/j.jbiosc.2013.09.012] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2013] [Revised: 09/06/2013] [Accepted: 09/18/2013] [Indexed: 10/26/2022]
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25
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Malefyt AP, Wu M, Vocelle DB, Kappes SJ, Lindeman SD, Chan C, Walton SP. Improved asymmetry prediction for short interfering RNAs. FEBS J 2014; 281:320-30. [PMID: 24393396 DOI: 10.1111/febs.12599] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/03/2013] [Revised: 08/28/2013] [Accepted: 09/26/2013] [Indexed: 01/10/2023]
Abstract
In the development of RNA interference therapeutics, merely selecting short interfering RNA (siRNA) sequences that are complementary to the mRNA target does not guarantee target silencing. Current algorithms for selecting siRNAs rely on many parameters, one of which is asymmetry, often predicted through calculation of the relative thermodynamic stabilities of the two ends of the siRNA. However, we have previously shown that highly active siRNA sequences are likely to have particular nucleotides at each 5'-end, independently of their thermodynamic asymmetry. Here, we describe an algorithm for predicting highly active siRNA sequences based only on these two asymmetry parameters. The algorithm uses end-sequence nucleotide preferences and predicted thermodynamic stabilities, each weighted on the basis of training data from the literature, to rank the probability that an siRNA sequence will have high or low activity. The algorithm successfully predicts weakly and highly active sequences for enhanced green fluorescent protein and protein kinase R. Use of these two parameters in combination improves the prediction of siRNA activity over current approaches for predicting asymmetry. Going forward, we anticipate that this approach to siRNA asymmetry prediction will be incorporated into the next generation of siRNA selection algorithms.
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Affiliation(s)
- Amanda P Malefyt
- Department of Chemical Engineering and Materials Science, Michigan State University, East Lansing, MI, USA
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26
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Stroynowska-Czerwinska A, Fiszer A, Krzyzosiak WJ. The panorama of miRNA-mediated mechanisms in mammalian cells. Cell Mol Life Sci 2014; 71:2253-70. [PMID: 24468964 PMCID: PMC4031385 DOI: 10.1007/s00018-013-1551-6] [Citation(s) in RCA: 77] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/24/2013] [Revised: 12/02/2013] [Accepted: 12/30/2013] [Indexed: 12/21/2022]
Abstract
MicroRNAs comprise a large family of short, non-coding RNAs that are present in most eukaryotic organisms and are typically involved in downregulating the expression of protein-coding genes. The detailed mechanisms of miRNA functioning in animals and plants have been under investigation for more than decade. In mammalian cells, miRNA guides the effector complex miRISC to bind with partially complementary sequences, usually within the 3′UTR of mRNAs, and inhibit protein synthesis with or without transcript degradation. In addition to these main mechanisms, several other modes of miRNA-mediated gene expression regulation have been described, but their scale and importance remain a matter of debate. In this review, we briefly summarize the pathway of miRNA precursor processing during miRNA biogenesis and continue with the description of the miRISC assembly process. Then, we present the miRNA-mediated mechanisms of gene expression regulation in detail, and we gather information concerning the proteins involved in these processes. In addition, we briefly refer to the current applications of miRNA mechanisms in therapeutic strategies. Finally, we highlight some of the remaining controversies surrounding the regulation of mammalian gene expression by miRNAs.
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Affiliation(s)
- Anna Stroynowska-Czerwinska
- Department of Molecular Biomedicine, Institute of Bioorganic Chemistry, Polish Academy of Sciences, ul. Noskowskiego 12/14, 61-704, Poznan, Poland
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27
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Yang L, Li X, Jiang S, Qiu L, Zhou F, Liu W, Jiang S. Characterization of Argonaute2 gene from black tiger shrimp (Penaeus monodon) and its responses to immune challenges. FISH & SHELLFISH IMMUNOLOGY 2014; 36:261-9. [PMID: 24262300 DOI: 10.1016/j.fsi.2013.11.010] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/25/2013] [Revised: 11/04/2013] [Accepted: 11/11/2013] [Indexed: 05/06/2023]
Abstract
Argonaute2 binds to a short guide RNA (microRNA or short interfering RNA) and guides RNAs direct RISC to complementary mRNAs that are targets for RISC-mediated gene silencing. Here we identified and characterized Argonaute2 from black tiger shrimp Penaeus monodon (designated as PmAgo2). The full-length cDNA of PmAgo2 contained a 5' untranslated region (UTR) of 106 bp, an open reading frame (ORF) of 2616 bp and a 3' UTR of 123 bp. The predicted PmAgo2 protein is 99.4 KDa with the theoretical isoelectric point of 9.54. PmAgo2 shared the highest similarity of amino acid with Marsupenaeus japonicus Argonaute2 and Litopenaeus vannamei Argonaute2, at 69.0% and 68.5%, respectively. Phylogenic analysis showed PmAgo2 clustered with shrimp Argonaute2, and closed to the group of insects. Real-time quantitative PCR showed that PmAgo2 was widely expressed in almost all examined tissues except eyestalk, with high expression in lymph and haemocyte. mRNA expression also revealed that PmAgo2 was significantly up-regulated by Staphylococcus aureus and White Spot Syndrome Virus (WSSV) in hepatopancreas. Furthermore, our study also confirmed that dsRNA and ssRNA homologous poly (I:C) and R848 activated the expression of PmAgo2. The result indicated that PmAgo2 responded to both bacterial infection and viral infection, especially, it may induce an ssRNA-mediated RNAi with other core members of siRNA pathway in black tiger shrimp.
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Affiliation(s)
- Lishi Yang
- Key Laboratory of South China Sea Fishery Resources Exploitation & Utilization, Ministry of Agriculture, The South China Sea Fisheries Research Institute, Chinese Academy of Fishery Sciences, Guangzhou 510300, PR China.
| | - Xiaolan Li
- Key Laboratory of South China Sea Fishery Resources Exploitation & Utilization, Ministry of Agriculture, The South China Sea Fisheries Research Institute, Chinese Academy of Fishery Sciences, Guangzhou 510300, PR China; College of Animal Science, South China Agriculture University, Guangzhou 510642, PR China
| | - Song Jiang
- Key Laboratory of South China Sea Fishery Resources Exploitation & Utilization, Ministry of Agriculture, The South China Sea Fisheries Research Institute, Chinese Academy of Fishery Sciences, Guangzhou 510300, PR China
| | - Lihua Qiu
- Key Laboratory of South China Sea Fishery Resources Exploitation & Utilization, Ministry of Agriculture, The South China Sea Fisheries Research Institute, Chinese Academy of Fishery Sciences, Guangzhou 510300, PR China
| | - Falin Zhou
- Key Laboratory of South China Sea Fishery Resources Exploitation & Utilization, Ministry of Agriculture, The South China Sea Fisheries Research Institute, Chinese Academy of Fishery Sciences, Guangzhou 510300, PR China
| | - Wenjing Liu
- Key Laboratory of South China Sea Fishery Resources Exploitation & Utilization, Ministry of Agriculture, The South China Sea Fisheries Research Institute, Chinese Academy of Fishery Sciences, Guangzhou 510300, PR China
| | - Shigui Jiang
- Key Laboratory of South China Sea Fishery Resources Exploitation & Utilization, Ministry of Agriculture, The South China Sea Fisheries Research Institute, Chinese Academy of Fishery Sciences, Guangzhou 510300, PR China.
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28
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Angart P, Vocelle D, Chan C, Walton SP. Design of siRNA Therapeutics from the Molecular Scale. Pharmaceuticals (Basel) 2013; 6:440-68. [PMID: 23976875 PMCID: PMC3749788 DOI: 10.3390/ph6040440] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Abstract
While protein-based therapeutics is well-established in the market, development of nucleic acid therapeutics has lagged. Short interfering RNAs (siRNAs) represent an exciting new direction for the pharmaceutical industry. These small, chemically synthesized RNAs can knock down the expression of target genes through the use of a native eukaryotic pathway called RNA interference (RNAi). Though siRNAs are routinely used in research studies of eukaryotic biological processes, transitioning the technology to the clinic has proven challenging. Early efforts to design an siRNA therapeutic have demonstrated the difficulties in generating a highly-active siRNA with good specificity and a delivery vehicle that can protect the siRNA as it is transported to a specific tissue. In this review article, we discuss design considerations for siRNA therapeutics, identifying criteria for choosing therapeutic targets, producing highly-active siRNA sequences, and designing an optimized delivery vehicle. Taken together, these design considerations provide logical guidelines for generating novel siRNA therapeutics.
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Affiliation(s)
- Phillip Angart
- Department of Chemical Engineering and Materials Science, Michigan State University, 428 S. Shaw Lane, Room 2527, East Lansing, MI 48824, USA; (P.A.); (D.V.); (C.C.)
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29
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Distinguishable in vitro binding mode of monomeric TRBP and dimeric PACT with siRNA. PLoS One 2013; 8:e63434. [PMID: 23658827 PMCID: PMC3642127 DOI: 10.1371/journal.pone.0063434] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2013] [Accepted: 04/01/2013] [Indexed: 01/14/2023] Open
Abstract
RNA interference (RNAi) is an evolutionally conserved posttranscriptional gene-silencing mechanism whereby small interfering RNA (siRNA) triggers sequence-specific cleavage of its cognate mRNA. Dicer, Argonaute (Ago), and either TAR-RNA binding protein (TRBP) or a protein activator of PKR (PACT) are the primary components of the RNAi pathway, and they comprise the core of a complex termed the RNA-induced silencing complex (RISC)-loading complex (RLC). TRBP and PACT share similar structural features including three dsRNA binding domains (dsRBDs), and a complex containing Dicer and either TRBP or PACT is considered to sense thermodynamic asymmetry of siRNA ends for guide strand selection. Thus, both TRBP and PACT are thought to participate in the RNAi pathway in an indistinguishable manner, but the differences in siRNA binding mode and the functional involvement of TRBP and PACT are poorly understood. Here, we show in vitro binding patterns of human TRBP and PACT to siRNA using electrophoresis mobility shift analysis and gel filtration chromatography. Our results clearly showed that TRBP and PACT have distinct in vitro siRNA binding patterns from each other. The results suggest that monomeric TRBP binds to siRNA at the higher affinity compared to the affinity for own homodimerization. In contrast, the affinity between PACT and siRNA is lower than that of homodimerization or that between TRBP and siRNA. Thus, siRNA may be more readily incorporated into RLC, interacting with TRBP (instead of PACT) in vivo.
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30
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The multiple functions of TRBP, at the hub of cell responses to viruses, stress, and cancer. Microbiol Mol Biol Rev 2013; 76:652-66. [PMID: 22933564 DOI: 10.1128/mmbr.00012-12] [Citation(s) in RCA: 69] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023] Open
Abstract
The TAR RNA binding protein (TRBP) has emerged as a key player in many cellular processes. First identified as a cellular protein that facilitates the replication of human immunodeficiency virus, TRBP has since been shown to inhibit the activation of protein kinase R (PKR), a protein involved in innate immune responses and the cellular response to stress. It also binds to the PKR activator PACT and regulates its function. TRBP also contributes to RNA interference as an integral part of the minimal RNA-induced silencing complex with Dicer and Argonaute proteins. Due to its multiple functions in the cell, TRBP is involved in oncogenesis when its sequence is mutated or its expression is deregulated. The depletion or overexpression of TRBP results in malignancy, suggesting that the balance of TRBP expression is key to normal cellular function. These studies show that TRBP is multifunctional and mediates cross talk between different pathways. Its activities at the molecular level impact the cellular function from normal development to cancer and the response to infections.
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Abstract
The proteins harboring double-stranded RNA binding domains (dsRBDs) play diverse functional roles such as RNA localization, splicing, editing, export, and translation, yet mechanistic basis and functional significance of dsRBDs remain unclear. To unravel this enigma, we investigated transactivation response RNA binding protein (TRBP) consisting of three dsRBDs, which functions in HIV replication, protein kinase R(PKR)-mediated immune response, and RNA silencing. Here we report an ATP-independent diffusion activity of TRBP exclusively on dsRNA in a length-dependent manner. The first two dsRBDs of TRBP are essential for diffusion, whereas the third dsRBD is dispensable. Two homologs of TRBP, PKR activator and R3D1-L, displayed the same diffusion, implying a universality of the diffusion activity among this protein family. Furthermore, a Dicer-TRBP complex on dsRNA exhibited dynamic diffusion, which was correlated with Dicer's catalytic activity. These results implicate the dsRNA-specific diffusion activity of TRBP that contributes to enhancing siRNA and miRNA processing by Dicer.
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Masliah G, Barraud P, Allain FHT. RNA recognition by double-stranded RNA binding domains: a matter of shape and sequence. Cell Mol Life Sci 2012; 70:1875-95. [PMID: 22918483 DOI: 10.1007/s00018-012-1119-x] [Citation(s) in RCA: 118] [Impact Index Per Article: 9.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2012] [Revised: 08/01/2012] [Accepted: 08/06/2012] [Indexed: 10/28/2022]
Abstract
The double-stranded RNA binding domain (dsRBD) is a small protein domain of 65-70 amino acids adopting an αβββα fold, whose central property is to bind to double-stranded RNA (dsRNA). This domain is present in proteins implicated in many aspects of cellular life, including antiviral response, RNA editing, RNA processing, RNA transport and, last but not least, RNA silencing. Even though proteins containing dsRBDs can bind to very specific dsRNA targets in vivo, the binding of dsRBDs to dsRNA is commonly believed to be shape-dependent rather than sequence-specific. Interestingly, recent structural information on dsRNA recognition by dsRBDs opens the possibility that this domain performs a direct readout of RNA sequence in the minor groove, allowing a global reconsideration of the principles describing dsRNA recognition by dsRBDs. We review in this article the current structural and molecular knowledge on dsRBDs, emphasizing the intricate relationship between the amino acid sequence, the structure of the domain and its RNA recognition capacity. We especially focus on the molecular determinants of dsRNA recognition and describe how sequence discrimination can be achieved by this type of domain.
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Affiliation(s)
- Grégoire Masliah
- Institute of Molecular Biology and Biophysics, ETH Zurich, Schafmattstrasse 20, 8093 Zürich, Switzerland
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Biogenesis and mechanism of action of small non-coding RNAs: insights from the point of view of structural biology. Int J Mol Sci 2012; 13:10268-10295. [PMID: 22949860 PMCID: PMC3431858 DOI: 10.3390/ijms130810268] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Revised: 07/17/2012] [Accepted: 08/02/2012] [Indexed: 01/17/2023] Open
Abstract
Non-coding RNAs are dominant in the genomic output of the higher organisms being not simply occasional transcripts with idiosyncratic functions, but constituting an extensive regulatory network. Among all the species of non-coding RNAs, small non-coding RNAs (miRNAs, siRNAs and piRNAs) have been shown to be in the core of the regulatory machinery of all the genomic output in eukaryotic cells. Small non-coding RNAs are produced by several pathways containing specialized enzymes that process RNA transcripts. The mechanism of action of these molecules is also ensured by a group of effector proteins that are commonly engaged within high molecular weight protein-RNA complexes. In the last decade, the contribution of structural biology has been essential to the dissection of the molecular mechanisms involved in the biosynthesis and function of small non-coding RNAs.
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Betancur JG, Tomari Y. Dicer is dispensable for asymmetric RISC loading in mammals. RNA (NEW YORK, N.Y.) 2012; 18:24-30. [PMID: 22106413 PMCID: PMC3261740 DOI: 10.1261/rna.029785.111] [Citation(s) in RCA: 55] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/06/2023]
Abstract
In flies, asymmetric loading of small RNA duplexes into Argonaute2-containing RNA-induced silencing complex (Ago2-RISC) requires Dicer-2/R2D2 heterodimer, which acts as a protein sensor for the thermodynamic stabilities of the ends of small RNA duplexes. However, the mechanism of small RNA asymmetry sensing in mammalian RISC assembly remains obscure. Here, we quantitatively examined RISC assembly and target silencing activity in the presence or absence of Dicer in mammals. Our data show that, unlike the well-characterized fly Ago2-RISC assembly pathway, mammalian Dicer is dispensable for asymmetric RISC loading in vivo and in vitro.
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Affiliation(s)
- Juan G. Betancur
- Institute of Molecular and Cellular Biosciences, The University of Tokyo, Bunkyo-ku, Tokyo 113-0032, Japan
- Department of Medical Genome Sciences, The University of Tokyo, Bunkyo-ku, Tokyo 113-0032, Japan
| | - Yukihide Tomari
- Institute of Molecular and Cellular Biosciences, The University of Tokyo, Bunkyo-ku, Tokyo 113-0032, Japan
- Department of Medical Genome Sciences, The University of Tokyo, Bunkyo-ku, Tokyo 113-0032, Japan
- Corresponding author.E-mail .
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35
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Dicer Proteins and Their Role in Gene Silencing Pathways. ACTA ACUST UNITED AC 2012. [DOI: 10.1016/b978-0-12-404741-9.00001-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/15/2023]
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36
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siRNA repositioning for guide strand selection by human Dicer complexes. Mol Cell 2011; 43:110-21. [PMID: 21726814 DOI: 10.1016/j.molcel.2011.05.028] [Citation(s) in RCA: 104] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/22/2010] [Revised: 03/15/2011] [Accepted: 05/16/2011] [Indexed: 01/03/2023]
Abstract
The human ribonuclease Dicer and its double-stranded RNA (dsRNA)-binding protein (dsRBP) partners TRBP and PACT play important roles in the biogenesis of regulatory RNAs. Following dicing, one dsRNA product strand is preferentially assembled into an RNA-induced silencing complex (RISC). The mechanism of strand selection in humans and the possible role of Dicer in this process remain unclear. Here we demonstrate that dsRNAs undergo significant repositioning within Dicer complexes following dicing. This repositioning enables directional binding of RNA duplexes, thereby biasing their orientation for guide strand selection according to the thermodynamic properties of the helix. Our findings indicate that Dicer is itself capable of sensing siRNA thermodynamic asymmetry regardless of the dsRBP to which it is bound. These results support a model in which Dicer employs two distinct RNA-binding sites-one for dsRNA processing and the other for sensing of siRNA thermodynamic asymmetry-during RISC loading in humans.
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37
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Abstract
The discovery of RNA interference (RNAi) generated considerable interest in developing short interfering RNAs (siRNAs) for understanding basic biology and as the active agents in a new variety of therapeutics. Early studies showed that selecting an active siRNA was not as straightforward as simply picking a sequence on the target mRNA and synthesizing the siRNA complementary to that sequence. As interest in applying RNAi has increased, the methods for identifying active siRNA sequences have evolved from focusing on the simplicity of synthesis and purification, to identifying preferred target sequences and secondary structures, to predicting the thermodynamic stability of the siRNA. As more specific details of the RNAi mechanism have been defined, these have been incorporated into more complex siRNA selection algorithms, increasing the reliability of selecting active siRNAs against a single target. Ultimately, design of the best siRNA therapeutics will require design of the siRNA itself, in addition to design of the vehicle and other components necessary for it to function in vivo. In this minireview, we summarize the evolution of siRNA selection techniques with a particular focus on one issue of current importance to the field, how best to identify those siRNA sequences likely to have high activity. Approaches to designing active siRNAs through chemical and structural modifications will also be highlighted. As the understanding of how to control the activity and specificity of siRNAs improves, the potential utility of siRNAs as human therapeutics will concomitantly grow.
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Affiliation(s)
- S Patrick Walton
- Department of Chemical Engineering and Materials Science, Michigan State University, East Lansing, MI 48824-1226, USA.
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Peacock H, Fostvedt E, Beal PA. Minor-groove-modulating adenosine replacements control protein binding and RNAi activity in siRNAs. ACS Chem Biol 2010; 5:1115-24. [PMID: 20863128 DOI: 10.1021/cb100245u] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
Short-interfering RNAs (siRNAs) are common tools in molecular biology; however, the development of RNAi-based therapeutics is limited by immunostimulatory and nonspecific effects mediated by off-target RNA-binding proteins. The RNA-dependent protein kinase (PKR) and adenosine deaminase that acts on RNA 1 (ADAR1) are two proteins implicated in RNAi off-target effects and share a common means of interaction with siRNAs through double-stranded RNA binding motifs (dsRBMs). Here we report the site-specific introduction of N²-propargyl 2-aminopurine into siRNAs and subsequent conversion to two bulky products via copper-catalyzed azide alkyne cycloaddition (CuAAC) with either N-azidoacetyl-mannosamine azide or N-ethylpiperidine azide. We observed position-specific effects on RNAi activity for modifications made to both the passenger and guide strands. These findings are rationalized in light of recent structural studies of components of the RNA-induced silencing complex (RISC) and RISC-loading complex (RLC). The most active siRNAs were assayed for binding affinity to PKR and ADAR1. PKR binding was significantly reduced by multiple modifications, regardless of size, and ADAR1 binding was reduced in a position- and size-sensitive manner. Our findings present a strategy for designing siRNAs that reduce off-target dsRBM-protein binding while retaining native RNAi activity.
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Affiliation(s)
- Hayden Peacock
- Department of Chemistry, University of California, Davis, California 95616, United States
| | - Erik Fostvedt
- Department of Chemistry, University of California, Davis, California 95616, United States
| | - Peter A. Beal
- Department of Chemistry, University of California, Davis, California 95616, United States
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Snead NM, Rossi JJ. Biogenesis and function of endogenous and exogenous siRNAs. WILEY INTERDISCIPLINARY REVIEWS-RNA 2010; 1:117-31. [PMID: 21956909 DOI: 10.1002/wrna.14] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
RNA interference (RNAi) is a sequence-specific gene silencing, or 'knockdown', mechanism facilitated by short duplex strands of RNA with sequence complementarity to target mRNAs. RNAi has many different forms, including posttranscriptional gene silencing (PTGS), and transcriptional gene silencing (TGS). Here, we review the biogenesis and function of an endogenous set of small RNA gene regulators, called microRNAs, as well as the mechanism of exogenously delivered small interfering RNAs. The potential applications of RNAi-based therapeutics are also highlighted.
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Affiliation(s)
- Nicholas M Snead
- Department of Molecular and Cellular Biology, Beckman Research Institute of the City of Hope, Duarte, CA 91010, USA
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