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Zhai R, Ruan K, Perez GF, Kubat M, Liu J, Hofacker I, Wuchty S. MicroRNA-Mediated Obstruction of Stem-loop Alternative Splicing (MIMOSAS): a global mechanism for the regulation of alternative splicing. RESEARCH SQUARE 2023:rs.3.rs-2977025. [PMID: 37546804 PMCID: PMC10402249 DOI: 10.21203/rs.3.rs-2977025/v1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 08/08/2023]
Abstract
While RNA secondary structures are critical to regulate alternative splicing of long-range pre-mRNA, the factors that modulate RNA structure and interfere with the recognition of the splice sites are largely unknown. Previously, we identified a small, non-coding microRNA that sufficiently affects stable stem structure formation of Nmnat pre-mRNA to regulate the outcomes of alternative splicing. However, the fundamental question remains whether such microRNA-mediated interference with RNA secondary structures is a global molecular mechanism for regulating mRNA splicing. We designed and refined a bioinformatic pipeline to predict candidate microRNAs that potentially interfere with pre-mRNA stem-loop structures, and experimentally verified splicing predictions of three different long-range pre-mRNAs in the Drosophila model system. Specifically, we observed that microRNAs can either disrupt or stabilize stem-loop structures to influence splicing outcomes. Our study suggests that MicroRNA-Mediated Obstruction of Stem-loop Alternative Splicing (MIMOSAS) is a novel regulatory mechanism for the transcriptome-wide regulation of alternative splicing, increases the repertoire of microRNA function and further indicates cellular complexity of post-transcriptional regulation.
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Affiliation(s)
| | - Kai Ruan
- University of Miami, Miller School of Medicine
| | | | | | - Jiaqi Liu
- University of Miami Miller School of Medicine
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2
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Ruan K, Perez GF, Liu J, Kubat M, Hofacker I, Wuchty S, Zhai RG. MicroRNA-Mediated Obstruction of Stem-loop Alternative Splicing (MIMOSAS): a global mechanism for the regulation of alternative splicing. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.04.14.536877. [PMID: 37425843 PMCID: PMC10327045 DOI: 10.1101/2023.04.14.536877] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 07/11/2023]
Abstract
While RNA secondary structures are critical to regulate alternative splicing of long-range pre-mRNA, the factors that modulate RNA structure and interfere with the recognition of the splice sites are largely unknown. Previously, we identified a small, non-coding microRNA that sufficiently affects stable stem structure formation of Nmnat pre-mRNA to regulate the outcomes of alternative splicing. However, the fundamental question remains whether such microRNA-mediated interference with RNA secondary structures is a global molecular mechanism for regulating mRNA splicing. We designed and refined a bioinformatic pipeline to predict candidate microRNAs that potentially interfere with pre-mRNA stem-loop structures, and experimentally verified splicing predictions of three different long-range pre-mRNAs in the Drosophila model system. Specifically, we observed that microRNAs can either disrupt or stabilize stem-loop structures to influence splicing outcomes. Our study suggests that MicroRNA-Mediated Obstruction of Stem-loop Alternative Splicing (MIMOSAS) is a novel regulatory mechanism for the transcriptome-wide regulation of alternative splicing, increases the repertoire of microRNA function and further indicates cellular complexity of post-transcriptional regulation. One-Sentence Summary MicroRNA-Mediated Obstruction of Stem-loop Alternative Splicing (MIMOSAS) is a novel regulatory mechanism for the transcriptome-wide regulation of alternative splicing.
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3
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Hu X, Yin G, Zhang Y, Zhu L, Huang H, Lv K. Recent advances in the functional explorations of nuclear microRNAs. Front Immunol 2023; 14:1097491. [PMID: 36911728 PMCID: PMC9992549 DOI: 10.3389/fimmu.2023.1097491] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2022] [Accepted: 02/10/2023] [Indexed: 02/24/2023] Open
Abstract
Approximately 22 nucleotide-long non-coding small RNAs (ncRNAs) play crucial roles in physiological and pathological activities, including microRNAs (miRNAs). Long ncRNAs often stay in the cytoplasm, modulating post-transcriptional gene expression. Briefly, miRNA binds with the target mRNA and builds a miRNA-induced silencing complex to silence the transcripts or prevent their translation. Interestingly, data from recent animal and plant studies suggested that mature miRNAs are present in the nucleus, where they regulate transcriptionally whether genes are activated or silenced. This significantly broadens the functional range of miRNAs. Here, we reviewed and summarized studies on the functions of nuclear miRNAs to better understand the modulatory networks associated with nuclear miRNAs.
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Affiliation(s)
- Xiaozhu Hu
- Central Laboratory, The First Affiliated Hospital of Wannan Medical College, Wuhu, China.,Key Laboratory of Non-Coding RNA Transformation Research of Anhui Higher Education Institutes (Wannan Medical College), Wuhu, China
| | - Guoquan Yin
- Central Laboratory, The First Affiliated Hospital of Wannan Medical College, Wuhu, China.,Key Laboratory of Non-Coding RNA Transformation Research of Anhui Higher Education Institutes (Wannan Medical College), Wuhu, China
| | - Yuan Zhang
- Central Laboratory, The First Affiliated Hospital of Wannan Medical College, Wuhu, China.,Key Laboratory of Non-Coding RNA Transformation Research of Anhui Higher Education Institutes (Wannan Medical College), Wuhu, China
| | - Liangyu Zhu
- Central Laboratory, The First Affiliated Hospital of Wannan Medical College, Wuhu, China.,Key Laboratory of Non-Coding RNA Transformation Research of Anhui Higher Education Institutes (Wannan Medical College), Wuhu, China
| | - Haoyu Huang
- Central Laboratory, The First Affiliated Hospital of Wannan Medical College, Wuhu, China.,Key Laboratory of Non-Coding RNA Transformation Research of Anhui Higher Education Institutes (Wannan Medical College), Wuhu, China
| | - Kun Lv
- Central Laboratory, The First Affiliated Hospital of Wannan Medical College, Wuhu, China.,Key Laboratory of Non-Coding RNA Transformation Research of Anhui Higher Education Institutes (Wannan Medical College), Wuhu, China
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4
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Li Z, Wang X, Zhou X, Wang J, Guan Z, Yang Z. Optimization in Chemical Modification of Single-Stranded siRNA Encapsulated by Neutral Cytidinyl/Cationic Lipids. Front Chem 2022; 10:843181. [PMID: 35345539 PMCID: PMC8957067 DOI: 10.3389/fchem.2022.843181] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/25/2021] [Accepted: 02/07/2022] [Indexed: 11/13/2022] Open
Abstract
Single-stranded siRNA (ss-siRNA) refers to the antisense strand of siRNA, which plays the role of gene silencing. Since single-stranded RNA is unstable, the present study employed a homemade neutral cytidinyl/cationic lipid delivery system and chemical modifications to improve its stability. The results showed that with the aid of mixed lipids, ss-siRNA could knock down 40% of target mRNA at 25 nM. With 2ʹ-F/2ʹ-OMe, phosphorothioate and 5ʹ-terminal phosphorylation, the optimized ss-siRNA could knock down 80% of target mRNA at 25 nM. Further knocking down AGO2, the ss-siRNAs could not effectively silence target mRNAs. Analysis of the biodistribution in vivo showed that ss-siRNA was less durable than siRNA, but spread more quickly to tissues. This study provides a safe and efficient ss-siRNA delivery and modification strategy, which lays the foundation for future works.
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5
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Johnson ST, Chu Y, Liu J, Corey DR. Impact of scaffolding protein TNRC6 paralogs on gene expression and splicing. RNA (NEW YORK, N.Y.) 2021; 27:1004-1016. [PMID: 34108231 PMCID: PMC8370741 DOI: 10.1261/rna.078709.121] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/09/2021] [Accepted: 06/04/2021] [Indexed: 05/11/2023]
Abstract
TNRC6 is a scaffolding protein that bridges interactions between small RNAs, argonaute (AGO) protein, and effector proteins to control gene expression. There are three paralogs in mammalian cells, TNRC6A, TNRC6B, and TNRC6C These paralogs have ∼40% amino acid sequence identity and the extent of their unique or redundant functions is unclear. Here, we use knockout cell lines, enhanced crosslinking immunoprecipitation (eCLIP), and high-throughput RNA sequencing (RNA-seq) to explore the roles of TNRC6 paralogs in RNA-mediated control of gene expression. We find that the paralogs are largely functionally redundant and changes in levels of gene expression are well-correlated with those observed in AGO knockout cell lines. Splicing changes observed in AGO knockout cell lines are also observed in TNRC6 knockout cells. These data further define the roles of the TNRC6 isoforms as part of the RNA interference (RNAi) machinery.
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Affiliation(s)
- Samantha T Johnson
- UT Southwestern Medical Center, Departments of Pharmacology and Biochemistry, Dallas, Texas 75205, USA
| | - Yongjun Chu
- UT Southwestern Medical Center, Departments of Pharmacology and Biochemistry, Dallas, Texas 75205, USA
| | - Jing Liu
- UT Southwestern Medical Center, Departments of Pharmacology and Biochemistry, Dallas, Texas 75205, USA
| | - David R Corey
- UT Southwestern Medical Center, Departments of Pharmacology and Biochemistry, Dallas, Texas 75205, USA
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6
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Hagiwara K, Honma M, Harumoto T, Harada K, Sawada T, Yamamoto J, Shinohara F. Development of Prodrug Type Circular siRNA for In Vivo Knockdown by Systemic Administration. Nucleic Acid Ther 2020; 30:346-364. [PMID: 33016851 DOI: 10.1089/nat.2020.0894] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
siRNAs are being developed as a novel therapeutic modality; however, problems impeding their application in extrahepatic tissues persist, including inadequate stability in biological environments and inefficient drug delivery system to target tissues. Thus, technological improvements that enable robust silencing of target messenger RNA (mRNA) in extrahepatic tissues are necessary. We developed prodrug type covalently closed siRNA (circular siRNA) as a novel nucleic acid agent to knockdown target genes in extrahepatic tissues by systemic administration without drug delivery components. Circular siRNA, which is chemically synthesizable, can assume optimal structures for efficient knockdown using its cleavable linker; namely, circular and linear structure in extracellular and intracellular environment, respectively. In this study, we investigated circular siRNA physicochemical properties, knockdown mechanism, and characteristics in vitro, as well as pharmacokinetics, accumulation, knockdown activity, and safety in vivo. Our circular siRNA exhibited higher stability against serum and exonucleases, increased cellular uptake, and stronger knockdown activity without transfection reagent in vitro than linear siRNA. Furthermore, after systemic administration to mice, circular siRNA showed prolonged circulation and improved knockdown activity in the liver, kidney, and muscle, without causing adverse effects. Circular siRNA may represent an additional platform for RNAi therapeutics, providing alternate solutions for disease treatment.
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Affiliation(s)
- Kenji Hagiwara
- Nucleic Acid Medicine Research Laboratories and Research Functions Unit, R&D Division, Kyowa Kirin Co., Ltd., Tokyo, Japan
| | - Masakazu Honma
- Nucleic Acid Medicine Research Laboratories and Research Functions Unit, R&D Division, Kyowa Kirin Co., Ltd., Tokyo, Japan
| | - Toshimasa Harumoto
- Nucleic Acid Medicine Research Laboratories and Research Functions Unit, R&D Division, Kyowa Kirin Co., Ltd., Tokyo, Japan
| | - Kenji Harada
- Management Office, Research Functions Unit, R&D Division, Kyowa Kirin Co., Ltd., Tokyo, Japan
| | - Takashi Sawada
- Nucleic Acid Medicine Research Laboratories and Research Functions Unit, R&D Division, Kyowa Kirin Co., Ltd., Tokyo, Japan
| | - Junichiro Yamamoto
- Nucleic Acid Medicine Research Laboratories and Research Functions Unit, R&D Division, Kyowa Kirin Co., Ltd., Tokyo, Japan
| | - Fumikazu Shinohara
- Management Office, Research Functions Unit, R&D Division, Kyowa Kirin Co., Ltd., Tokyo, Japan
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7
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MicroRNAs: Diverse Mechanisms of Action and Their Potential Applications as Cancer Epi-Therapeutics. Biomolecules 2020; 10:biom10091285. [PMID: 32906681 PMCID: PMC7565521 DOI: 10.3390/biom10091285] [Citation(s) in RCA: 24] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2020] [Revised: 08/10/2020] [Accepted: 09/02/2020] [Indexed: 12/23/2022] Open
Abstract
Usually, miRNAs function post-transcriptionally, by base-pairing with the 3′UTR of target mRNAs, repressing protein synthesis in the cytoplasm. Furthermore, other regions including gene promoters, as well as coding and 5′UTR regions of mRNAs are able to interact with miRNAs. In recent years, miRNAs have emerged as important regulators of both translational and transcriptional programs. The expression of miRNA genes, similar to protein-coding genes, can be epigenetically regulated, in turn miRNA molecules (named epi-miRs) are able to regulate epigenetic enzymatic machinery. The most recent line of evidence indicates that miRNAs can influence physiological processes, such as embryonic development, cell proliferation, differentiation, and apoptosis as well as pathological processes (e.g., tumorigenesis) through epigenetic mechanisms. Some tumor types show repression of tumor-suppressor epi-miRs resulting in cancer progression and metastasis, hence these molecules have become novel therapeutic targets in the last few years. This review provides information about miRNAs involvement in the various levels of transcription and translation regulation, as well as discusses therapeutic potential of tumor-suppressor epi-miRs used in in vitro and in vivo anti-cancer therapy.
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8
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Park J, Zhu Y, Tao X, Brazill JM, Li C, Wuchty S, Zhai RG. MicroRNA miR-1002 Enhances NMNAT-Mediated Stress Response by Modulating Alternative Splicing. iScience 2019; 19:1048-1064. [PMID: 31522116 PMCID: PMC6745518 DOI: 10.1016/j.isci.2019.08.052] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2018] [Revised: 05/07/2019] [Accepted: 08/27/2019] [Indexed: 11/30/2022] Open
Abstract
Understanding endogenous regulation of stress resistance and homeostasis maintenance is critical to developing neuroprotective therapies. Nicotinamide mononucleotide adenylyltransferase (NMNAT) is a conserved essential enzyme that confers extraordinary protection and stress resistance in many neurodegenerative disease models. Drosophila Nmnat is alternatively spliced to two mRNA variants, RA and RB. RB translates to protein isoform PD with robust protective activity and is upregulated upon stress to confer enhanced neuroprotection. The mechanisms regulating the alternative splicing and stress response of NMNAT remain unclear. We have discovered a Drosophila microRNA, dme-miR-1002, which promotes the splicing of NMNAT pre-mRNA to RB by disrupting a pre-mRNA stem-loop structure. NMNAT pre-mRNA is preferentially spliced to RA in basal conditions, whereas miR-1002 enhances NMNAT PD-mediated stress protection by binding via RISC component Argonaute1 to the pre-mRNA, facilitating the splicing switch to RB. These results outline a new process for microRNAs in regulating alternative splicing and modulating stress resistance.
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Affiliation(s)
- Joun Park
- Department of Molecular and Cellular Pharmacology, University of Miami Miller School of Medicine, Miami, FL 33136, USA; Program in Neuroscience, University of Miami Miller School of Medicine, Miami, FL 33136, USA
| | - Yi Zhu
- Department of Molecular and Cellular Pharmacology, University of Miami Miller School of Medicine, Miami, FL 33136, USA; Program in Molecular and Cellular Pharmacology, University of Miami Miller School of Medicine, Miami, FL 33136, USA
| | - Xianzun Tao
- Department of Molecular and Cellular Pharmacology, University of Miami Miller School of Medicine, Miami, FL 33136, USA
| | - Jennifer M Brazill
- Department of Molecular and Cellular Pharmacology, University of Miami Miller School of Medicine, Miami, FL 33136, USA; Program in Molecular and Cellular Pharmacology, University of Miami Miller School of Medicine, Miami, FL 33136, USA
| | - Chong Li
- Department of Molecular and Cellular Pharmacology, University of Miami Miller School of Medicine, Miami, FL 33136, USA; Program in Human Genetics and Genomics, University of Miami Miller School of Medicine, Miami, FL 33136, USA
| | - Stefan Wuchty
- Department of Computer Science, University of Miami, Coral Gables, FL 33146, USA
| | - R Grace Zhai
- Department of Molecular and Cellular Pharmacology, University of Miami Miller School of Medicine, Miami, FL 33136, USA; Program in Neuroscience, University of Miami Miller School of Medicine, Miami, FL 33136, USA; Program in Molecular and Cellular Pharmacology, University of Miami Miller School of Medicine, Miami, FL 33136, USA; Program in Human Genetics and Genomics, University of Miami Miller School of Medicine, Miami, FL 33136, USA.
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9
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Ma X, Zuo Z, Shao W, Jin Y, Meng Y. The expanding roles of Argonautes: RNA interference, splicing and beyond. Brief Funct Genomics 2019; 17:191-197. [PMID: 29240875 DOI: 10.1093/bfgp/elx045] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
Argonaute (AGO) protein family is highly conserved in eukaryotes and prokaryotes, reflecting its evolutionarily indispensible role in maintaining normal life cycle of the organisms. Small RNA-guided, AGO-dependent RNA interference (RNAi) is a well-studied pathway for gene expression regulation, which can be performed at transcriptional, posttranscriptional or translational level. In addition to RNAi, growing pieces of evidence point to a novel role of AGOs in pre-mRNA (messenger RNA precursor) splicing in animals. Many noncoding RNAs (ncRNAs) share common structural features with protein-coding genes, indicating that these ncRNAs might be subject to AGO-mediated splicing. Finally, we provide a comprehensive view that RNAi, transcription and RNA splicing are highly interactive processes, all of which involve several key factors such as AGOs. In this regard, the AGO proteins contribute to orchestrate an exquisite gene regulatory network in vivo. However, more research efforts are needed to reach a thorough understanding of the AGO activities.
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10
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Liu J, Liu Z, Corey DR. The Requirement for GW182 Scaffolding Protein Depends on Whether Argonaute Is Mediating Translation, Transcription, or Splicing. Biochemistry 2018; 57:5247-5256. [PMID: 30086238 DOI: 10.1021/acs.biochem.8b00602] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
GW182 and argonaute 2 (AGO2) are core proteins of the RNA interference complex. GW182 is a scaffolding protein that physically associates with AGO2 and bridges its interactions with other proteins. A fundamental problem in biology is how scaffolding proteins adapt or contribute to differing functional demands within cells. Here we test the necessity for human GW182 proteins (paralogs TNRC6A, TNRC6B, and TNRC6C) for several mechanisms of small duplex RNA-mediated control of gene expression, including translational silencing by miRNAs, translational silencing by siRNAs, transcriptional silencing, transcriptional activation, and splicing. We find that GW182 is required for transcriptional activation and for the activity of miRNAs but is dispensable for the regulation of splicing, transcriptional silencing, and the action of siRNAs. AGO2, by contrast, is necessary for each of these processes. Our data suggest that GW182 does not alter AGO2 to make it active. Instead, GW182 organizes protein complexes around AGO2. Sometimes this higher level of organization is necessary, and sometimes it is not. AGO2 and GW182 offer an example for how a partnership between a scaffolding protein and a functional protein can be powerful but not obligatory.
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Affiliation(s)
- Jing Liu
- Departments of Pharmacology and Biochemistry , The University of Texas Southwestern Medical Center , Dallas , Texas 75390 , United States
| | - Zhongtian Liu
- Departments of Pharmacology and Biochemistry , The University of Texas Southwestern Medical Center , Dallas , Texas 75390 , United States.,College of Animal Science and Technology , Northwest A&F University , Shaanxi , China 712100
| | - David R Corey
- Departments of Pharmacology and Biochemistry , The University of Texas Southwestern Medical Center , Dallas , Texas 75390 , United States
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11
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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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12
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Hu J, Rigo F, Prakash TP, Corey DR. Recognition of c9orf72 Mutant RNA by Single-Stranded Silencing RNAs. Nucleic Acid Ther 2017; 27:87-94. [PMID: 28005462 PMCID: PMC5372765 DOI: 10.1089/nat.2016.0655] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2016] [Accepted: 11/15/2016] [Indexed: 01/09/2023] Open
Abstract
Mutations within the chromosome 9 open reading frame 72 (c9orf72) gene are associated with both familial amyotrophic lateral sclerosis and frontotemporal dementia. The mutation leads to an expanded GGGGCC hexanucleotide repeat within the first intron of c9orf72 and an expanded CCCCGG repeat within a corresponding antisense transcript. Both the mutant intronic and antisense RNAs have been implicated in disease. We have previously reported that duplex RNAs complementary to the repeats can recognize disease-causing RNA and block detection of nuclear foci formed by the mutant transcripts. Here, we test the hypothesis that inhibition can also be achieved by single-stranded silencing RNAs (ss-siRNAs). ss-siRNAs are single-stranded antisense oligonucleotides (ASOs) that function through RNAi interference (RNAi) to silence gene expression. ss-siRNAs can block the expanded repeats within both intronic RNA and the antisense transcripts. Inhibition is more potent than by analogous duplex RNAs. Our data suggest that the potent effects on foci are caused by a combination of mechanisms including RNAi and direct binding of the ss-siRNA to the target transcripts. These findings reinforce the suggestion that ss-siRNAs combine the favorable properties of duplex RNA and single-stranded ASOs.
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Affiliation(s)
- Jiaxin Hu
- 1 Department of Pharmacology, UT Southwestern Medical Center at Dallas , Dallas, Texas
- 2 Department of Biochemistry, UT Southwestern Medical Center at Dallas , Dallas, Texas
| | - Frank Rigo
- 3 Ionis Pharmaceuticals , Carlsbad, California
| | | | - David R Corey
- 1 Department of Pharmacology, UT Southwestern Medical Center at Dallas , Dallas, Texas
- 2 Department of Biochemistry, UT Southwestern Medical Center at Dallas , Dallas, Texas
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13
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Catalanotto C, Cogoni C, Zardo G. MicroRNA in Control of Gene Expression: An Overview of Nuclear Functions. Int J Mol Sci 2016; 17:ijms17101712. [PMID: 27754357 PMCID: PMC5085744 DOI: 10.3390/ijms17101712] [Citation(s) in RCA: 752] [Impact Index Per Article: 94.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/26/2016] [Revised: 10/04/2016] [Accepted: 10/07/2016] [Indexed: 12/14/2022] Open
Abstract
The finding that small non-coding RNAs (ncRNAs) are able to control gene expression in a sequence specific manner has had a massive impact on biology. Recent improvements in high throughput sequencing and computational prediction methods have allowed the discovery and classification of several types of ncRNAs. Based on their precursor structures, biogenesis pathways and modes of action, ncRNAs are classified as small interfering RNAs (siRNAs), microRNAs (miRNAs), PIWI-interacting RNAs (piRNAs), endogenous small interfering RNAs (endo-siRNAs or esiRNAs), promoter associate RNAs (pRNAs), small nucleolar RNAs (snoRNAs) and sno-derived RNAs. Among these, miRNAs appear as important cytoplasmic regulators of gene expression. miRNAs act as post-transcriptional regulators of their messenger RNA (mRNA) targets via mRNA degradation and/or translational repression. However, it is becoming evident that miRNAs also have specific nuclear functions. Among these, the most studied and debated activity is the miRNA-guided transcriptional control of gene expression. Although available data detail quite precisely the effectors of this activity, the mechanisms by which miRNAs identify their gene targets to control transcription are still a matter of debate. Here, we focus on nuclear functions of miRNAs and on alternative mechanisms of target recognition, at the promoter lavel, by miRNAs in carrying out transcriptional gene silencing.
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Affiliation(s)
- Caterina Catalanotto
- Department of Cellular Biotechnologies and Hematology, University of Rome Sapienza, Rome 00179, Italy.
| | - Carlo Cogoni
- Department of Cellular Biotechnologies and Hematology, University of Rome Sapienza, Rome 00179, Italy.
| | - Giuseppe Zardo
- Department of Cellular Biotechnologies and Hematology, University of Rome Sapienza, Rome 00179, Italy.
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14
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Kalantari R, Hicks JA, Li L, Gagnon KT, Sridhara V, Lemoff A, Mirzaei H, Corey DR. Stable association of RNAi machinery is conserved between the cytoplasm and nucleus of human cells. RNA (NEW YORK, N.Y.) 2016; 22:1085-98. [PMID: 27198507 PMCID: PMC4911916 DOI: 10.1261/rna.056499.116] [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: 03/02/2016] [Accepted: 04/25/2016] [Indexed: 05/25/2023]
Abstract
Argonaute 2 (AGO2), the catalytic engine of RNAi, is typically associated with inhibition of translation in the cytoplasm. AGO2 has also been implicated in nuclear processes including transcription and splicing. There has been little insight into AGO2's nuclear interactions or how they might differ relative to cytoplasm. Here we investigate the interactions of cytoplasmic and nuclear AGO2 using semi-quantitative mass spectrometry. Mass spectrometry often reveals long lists of candidate proteins, complicating efforts to rigorously discriminate true interacting partners from artifacts. We prioritized candidates using orthogonal analytical strategies that compare replicate mass spectra of proteins associated with Flag-tagged and endogenous AGO2. Interactions with TRNC6A, TRNC6B, TNRC6C, and AGO3 are conserved between nuclei and cytoplasm. TAR binding protein interacted stably with cytoplasmic AGO2 but not nuclear AGO2, consistent with strand loading in the cytoplasm. Our data suggest that interactions between functionally important components of RNAi machinery are conserved between the nucleus and cytoplasm but that accessory proteins differ. Orthogonal analysis of mass spectra is a powerful approach to streamlining identification of protein partners.
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Affiliation(s)
- Roya Kalantari
- Department of Pharmacology, Department of Biochemistry, University of Texas Southwestern Medical Center, Dallas, Texas 75390, USA
| | - Jessica A Hicks
- Department of Pharmacology, Department of Biochemistry, University of Texas Southwestern Medical Center, Dallas, Texas 75390, USA
| | - Liande Li
- Department of Pharmacology, Department of Biochemistry, University of Texas Southwestern Medical Center, Dallas, Texas 75390, USA
| | - Keith T Gagnon
- Department of Biochemistry and Molecular Biology, Southern Illinois University, Carbondale, Illinois 62901, USA
| | - Viswanadham Sridhara
- Department of Biochemistry, University of Texas Southwestern Medical Center, Dallas, Texas 75390, USA
| | - Andrew Lemoff
- Department of Biochemistry, University of Texas Southwestern Medical Center, Dallas, Texas 75390, USA
| | - Hamid Mirzaei
- Department of Biochemistry, University of Texas Southwestern Medical Center, Dallas, Texas 75390, USA
| | - David R Corey
- Department of Pharmacology, Department of Biochemistry, University of Texas Southwestern Medical Center, Dallas, Texas 75390, USA
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15
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Pendergraff HM, Debacker AJ, Watts JK. Single-Stranded Silencing RNAs: Hit Rate and Chemical Modification. Nucleic Acid Ther 2016; 26:216-22. [PMID: 27123752 DOI: 10.1089/nat.2015.0557] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
Single-stranded silencing RNAs (ss-siRNAs) are chemically modified single-stranded oligomers that engage the RNA interference machinery normally used by duplex RNAs to silence gene expression. ss-siRNAs have the potential to combine advantages of antisense oligonucleotides and siRNAs. Previous work has explored the chemistry of the phosphate and the oligonucleotide body. We now describe the process of attempting to develop and optimize ss-siRNAs based on five active siRNA duplexes. Three of the sequences failed to show any activity as ss-siRNAs, and in two of those cases the ss-siRNAs showed significantly increased toxicity relative to the parent duplexes. For the two sequences that did work well as ss-siRNAs, we show that the chemistry of the 3'-terminal dinucleotide also has a significant effect on the potency of ss-siRNAs. Previously published work on ss-siRNAs has been based on a 2'-O-methoxyethyl-RNA (MOE) dinucleotide at the 3'-terminus. To our surprise, oligomers containing 2'-O-Me-RNA modifications at the 3'-terminus showed significantly improved potency and activity relative to those modified with MOE at the same sites. Oligonucleotides with two locked nucleic acid units at the 3'-terminus showed improved activity over the MOE-modified analog for one sequence. Importantly, the fact that 2'-O-Me-RNA works so well makes the ss-siRNA approach accessible to a wider range of researchers since it can be achieved with inexpensive commercially available modifications.
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Affiliation(s)
- Hannah M Pendergraff
- 1 Department of Chemistry and Institute for Life Sciences, University of Southampton , United Kingdom
| | - Alexandre J Debacker
- 1 Department of Chemistry and Institute for Life Sciences, University of Southampton , United Kingdom .,2 RNA Therapeutics Institute and Department of Biochemistry and Molecular Pharmacology, UMass Medical School, Worcester, Massachusetts
| | - Jonathan K Watts
- 1 Department of Chemistry and Institute for Life Sciences, University of Southampton , United Kingdom .,2 RNA Therapeutics Institute and Department of Biochemistry and Molecular Pharmacology, UMass Medical School, Worcester, Massachusetts
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Kalantari R, Chiang CM, Corey DR. Regulation of mammalian transcription and splicing by Nuclear RNAi. Nucleic Acids Res 2016; 44:524-37. [PMID: 26612865 PMCID: PMC4737150 DOI: 10.1093/nar/gkv1305] [Citation(s) in RCA: 72] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/22/2015] [Revised: 11/04/2015] [Accepted: 11/09/2015] [Indexed: 12/21/2022] Open
Abstract
RNA interference (RNAi) is well known as a mechanism for controlling mammalian mRNA translation in the cytoplasm, but what would be the consequences if it also functions in cell nuclei? Although RNAi has also been found in nuclei of plants, yeast, and other organisms, there has been relatively little progress towards understanding the potential involvement of mammalian RNAi factors in nuclear processes including transcription and splicing. This review summarizes evidence for mammalian RNAi factors in cell nuclei and mechanisms that might contribute to the control of gene expression. When RNAi factors bind small RNAs, they form ribonucleoprotein complexes that can be selective for target sequences within different classes of nuclear RNA substrates. The versatility of nuclear RNAi may supply a previously underappreciated layer of regulation to transcription, splicing, and other nuclear processes.
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Affiliation(s)
- Roya Kalantari
- Departments of Pharmacology & Biochemistry, University of Texas Southwestern Medical Center, 6001 Forest Park Road, Dallas, TX 75390-9041, USA
| | - Cheng-Ming Chiang
- Departments of Pharmacology & Biochemistry, University of Texas Southwestern Medical Center, 6001 Forest Park Road, Dallas, TX 75390-9041, USA Simmons Comprehensive Cancer Center, University of Texas Southwestern Medical Center, 6001 Forest Park Road, Dallas, TX 75390-8807, USA
| | - David R Corey
- Departments of Pharmacology & Biochemistry, University of Texas Southwestern Medical Center, 6001 Forest Park Road, Dallas, TX 75390-9041, USA
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