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Chen S, Jiang Z, Li Q, Pan W, Chen Y, Liu J. Viral RNA capping: Mechanisms and antiviral therapy. J Med Virol 2024; 96:e29622. [PMID: 38682614 DOI: 10.1002/jmv.29622] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2023] [Revised: 03/25/2024] [Accepted: 04/11/2024] [Indexed: 05/01/2024]
Abstract
RNA capping is an essential trigger for protein translation in eukaryotic cells. Many viruses have evolved various strategies for initiating the translation of viral genes and generating progeny virions in infected cells via synthesizing cap structure or stealing the RNA cap from nascent host messenger ribonucleotide acid (mRNA). In addition to protein translation, a new understanding of the role of the RNA cap in antiviral innate immunity has advanced the field of mRNA synthesis in vitro and therapeutic applications. Recent studies on these viral RNA capping systems have revealed startlingly diverse ways and molecular machinery. A comprehensive understanding of how viruses accomplish the RNA capping in infected cells is pivotal for designing effective broad-spectrum antiviral therapies. Here we systematically review the contemporary insights into the RNA-capping mechanisms employed by viruses causing human and animal infectious diseases, while also highlighting its impact on host antiviral innate immune response. The therapeutic applications of targeting RNA capping against viral infections and the development of RNA-capping inhibitors are also summarized.
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Affiliation(s)
- Saini Chen
- National Key Laboratory of Veterinary Public Health and Safety, College of Veterinary Medicine, China Agricultural University, Beijing, China
| | - Zhimin Jiang
- National Key Laboratory of Veterinary Public Health and Safety, College of Veterinary Medicine, China Agricultural University, Beijing, China
| | - Qiuchen Li
- National Key Laboratory of Veterinary Public Health and Safety, College of Veterinary Medicine, China Agricultural University, Beijing, China
| | - Wenliang Pan
- National Key Laboratory of Veterinary Public Health and Safety, College of Veterinary Medicine, China Agricultural University, Beijing, China
| | - Yu Chen
- National Key Laboratory of Veterinary Public Health and Safety, College of Veterinary Medicine, China Agricultural University, Beijing, China
| | - Jinhua Liu
- National Key Laboratory of Veterinary Public Health and Safety, College of Veterinary Medicine, China Agricultural University, Beijing, China
- Key Laboratory for Prevention and Control of Avian Influenza and Other Major Poultry Diseases, Ministry of Agriculture and Rural Affairs, College of Veterinary Medicine, China Agricultural University, Beijing, China
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Linder B, Jaffrey SR. Discovering and Mapping the Modified Nucleotides That Comprise the Epitranscriptome of mRNA. Cold Spring Harb Perspect Biol 2019; 11:11/6/a032201. [PMID: 31160350 DOI: 10.1101/cshperspect.a032201] [Citation(s) in RCA: 40] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
An important mechanism of gene expression regulation is the regulated modification of nucleotides in messenger RNA (mRNA). These modified nucleotides affect mRNA translation, stability, splicing, and other processes. A cluster of nucleotide modifications is found adjacent to the mRNA cap structure and another set can be found internally within transcripts. The most prominent modifications are methylations of adenosine to form either N 6-methyladenosine (m6A), an internal modified nucleotide, or N 6,2'-O-dimethyladenosine (m6Am), which is found exclusively at the first templated nucleotide of certain mRNAs. In addition, other rare modified nucleotides have been identified and together these form the epitranscriptomic code of mRNA. In the case of some modified nucleotides, the presence, location, or abundance is a subject of debate. Here, we review the methods that enable the discovery of modified nucleotides and how these approaches can be used to map epitranscriptomic modifications in mRNA.
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Affiliation(s)
- Bastian Linder
- Genome Biology Unit, European Molecular Biology Laboratory, Heidelberg 69117, Germany.,Department of Pharmacology, Weill Cornell Medicine, New York, New York 10065
| | - Samie R Jaffrey
- Department of Pharmacology, Weill Cornell Medicine, New York, New York 10065
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Sarvestani ST, Stunden HJ, Behlke MA, Forster SC, McCoy CE, Tate MD, Ferrand J, Lennox KA, Latz E, Williams BRG, Gantier MP. Sequence-dependent off-target inhibition of TLR7/8 sensing by synthetic microRNA inhibitors. Nucleic Acids Res 2014; 43:1177-88. [PMID: 25539920 PMCID: PMC4333393 DOI: 10.1093/nar/gku1343] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023] Open
Abstract
Anti-microRNA (miRNA) oligonucleotides (AMOs) with 2'-O-Methyl (2'OMe) residues are commonly used to study miRNA function and can achieve high potency, with low cytotoxicity. Not withstanding this, we demonstrate the sequence-dependent capacity of 2'OMe AMOs to inhibit Toll-like receptor (TLR) 7 and 8 sensing of immunostimulatory RNA, independent of their miRNA-targeting function. Through a screen of 29 AMOs targeting common miRNAs, we found a subset of sequences highly inhibitory to TLR7 sensing in mouse macrophages. Interspecies conservation of this inhibitory activity was confirmed on TLR7/8 activity in human peripheral blood mononuclear cells. Significantly, we identified a core motif governing the inhibitory activity of these AMOs, which is present in more than 50 AMOs targeted to human miRNAs in miRBaseV20. DNA/locked nucleic acids (LNA) AMOs synthesized with a phosphorothioate backbone also inhibited TLR7 sensing in a sequence-dependent manner, demonstrating that the off-target effects of AMOs are not restricted to 2'OMe modification. Taken together, our work establishes the potential for off-target effects of AMOs on TLR7/8 function, which should be taken into account in their therapeutic development and in vivo application.
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Affiliation(s)
- Soroush T Sarvestani
- Centre for Cancer Research, MIMR-PHI Institute of Medical Research, Clayton, Victoria 3168, Australia Department of Molecular and Translational Science, Monash University, Clayton, Victoria 3168, Australia
| | - H James Stunden
- Institute of Innate Immunity, Biomedical Center, University Hospitals Bonn, Bonn 53127, Germany
| | - Mark A Behlke
- Integrated DNA Technologies Inc., Coralville, IA 52241, USA
| | - Samuel C Forster
- Host-Microbiota Interactions Laboratory, Wellcome Trust Sanger Institute, Hinxton, CB10 1SA, UK
| | - Claire E McCoy
- Centre for Cancer Research, MIMR-PHI Institute of Medical Research, Clayton, Victoria 3168, Australia Department of Molecular and Translational Science, Monash University, Clayton, Victoria 3168, Australia
| | - Michelle D Tate
- Department of Molecular and Translational Science, Monash University, Clayton, Victoria 3168, Australia Centre for Innate Immunity and Infectious Diseases, MIMR-PHI Institute of Medical Research, Clayton, Victoria 3168, Australia
| | - Jonathan Ferrand
- Centre for Cancer Research, MIMR-PHI Institute of Medical Research, Clayton, Victoria 3168, Australia Department of Molecular and Translational Science, Monash University, Clayton, Victoria 3168, Australia
| | - Kim A Lennox
- Integrated DNA Technologies Inc., Coralville, IA 52241, USA
| | - Eicke Latz
- Institute of Innate Immunity, Biomedical Center, University Hospitals Bonn, Bonn 53127, Germany Division of Infectious Diseases & Immunology, University of Massachusetts Medical School, Worcester, MA 01605, USA Deutsches Zentrum für Neurodegenerative Erkrankungen, Bonn 53127, Germany
| | - Bryan R G Williams
- Centre for Cancer Research, MIMR-PHI Institute of Medical Research, Clayton, Victoria 3168, Australia Department of Molecular and Translational Science, Monash University, Clayton, Victoria 3168, Australia
| | - Michael P Gantier
- Centre for Cancer Research, MIMR-PHI Institute of Medical Research, Clayton, Victoria 3168, Australia Department of Molecular and Translational Science, Monash University, Clayton, Victoria 3168, Australia
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Werner M, Purta E, Kaminska KH, Cymerman IA, Campbell DA, Mittra B, Zamudio JR, Sturm NR, Jaworski J, Bujnicki JM. 2'-O-ribose methylation of cap2 in human: function and evolution in a horizontally mobile family. Nucleic Acids Res 2011; 39:4756-68. [PMID: 21310715 PMCID: PMC3113572 DOI: 10.1093/nar/gkr038] [Citation(s) in RCA: 99] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022] Open
Abstract
The 5′ cap of human messenger RNA consists of an inverted 7-methylguanosine linked to the first transcribed nucleotide by a unique 5′–5′ triphosphate bond followed by 2′-O-ribose methylation of the first and often the second transcribed nucleotides, likely serving to modify efficiency of transcript processing, translation and stability. We report the validation of a human enzyme that methylates the ribose of the second transcribed nucleotide encoded by FTSJD1, henceforth renamed HMTR2 to reflect function. Purified recombinant hMTr2 protein transfers a methyl group from S-adenosylmethionine to the 2′-O-ribose of the second nucleotide of messenger RNA and small nuclear RNA. Neither N7 methylation of the guanosine cap nor 2′-O-ribose methylation of the first transcribed nucleotide are required for hMTr2, but the presence of cap1 methylation increases hMTr2 activity. The hMTr2 protein is distributed throughout the nucleus and cytosol, in contrast to the nuclear hMTr1. The details of how and why specific transcripts undergo modification with these ribose methylations remains to be elucidated. The 2′-O-ribose RNA cap methyltransferases are present in varying combinations in most eukaryotic and many viral genomes. With the capping enzymes in hand their biological purpose can be ascertained.
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Affiliation(s)
- Maria Werner
- International Institute of Molecular and Cell Biology in Warsaw, ul. Ks. Trojdena 4, 02-109 Warsaw, Poland
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Pillutla RC, Yue Z, Maldonado E, Shatkin AJ. Recombinant human mRNA cap methyltransferase binds capping enzyme/RNA polymerase IIo complexes. J Biol Chem 1998; 273:21443-6. [PMID: 9705270 DOI: 10.1074/jbc.273.34.21443] [Citation(s) in RCA: 58] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Guanine N-7 methylation is an essential step in the formation of the m7GpppN cap structure that is characteristic of eukaryotic mRNA 5' ends. The terminal 7-methylguanosine is recognized by cap-binding proteins that facilitate key events in gene expression including mRNA processing, transport, and translation. Here we describe the cloning, primary structure, and properties of human RNA (guanine-7-)methyltransferase. Sequence alignment of the 476-amino acid human protein with the corresponding yeast ABD1 enzyme demonstrated the presence of several conserved motifs known to be required for methyltransferase activity. We also identified a Drosophila open reading frame that encodes a putative RNA (guanine-7-)methyltransferase and contains these motifs. Recombinant human methyltransferase transferred a methyl group from S-adenosylmethionine to GpppG 5'ends, which are formed on RNA polymerase II transcripts by the sequential action of RNA 5'-triphosphatase and guanylyltransferase activities in the bifunctional mammalian capping enzyme. Binding studies demonstrated that the human cap methyltransferase associated with recombinant capping enzyme. Consistent with selective capping of RNA polymerase II transcripts, methyltransferase also formed ternary complexes with capping enzyme and the elongating form of RNA polymerase II.
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Affiliation(s)
- R C Pillutla
- Center for Advanced Biotechnology and Medicine, Piscataway, New Jersey 08854-5638, USA
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Backlund PS, Carotti D, Cantoni GL. Effects of the S-adenosylhomocysteine hydrolase inhibitors 3-deazaadenosine and 3-deazaaristeromycin on RNA methylation and synthesis. EUROPEAN JOURNAL OF BIOCHEMISTRY 1986; 160:245-51. [PMID: 3769925 DOI: 10.1111/j.1432-1033.1986.tb09963.x] [Citation(s) in RCA: 32] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Abstract
The effects of 3-deazaaristeromycin and 3-deazaadenosine on RNA methylation and synthesis were examined in the mouse macrophage cell line, RAW264. S-Adenosylhomocysteine accumulated in cells incubated with 3-deazaaristeromycin while S-3-deazaadenosylhomocysteine was the major product in cells incubated with 3-deazaadenosine and homocysteine thiolactone. RNA methylation was inhibited to a similar extent by the accumulation of either S-adenosylhomocysteine or S-3-deazaadenosylhomocysteine, with S-adenosylhomocysteine being a slightly better inhibitor. In mRNA, the synthesis of N6-methyladenosine and N6-methyl-2'-O-methyladenosine were inhibited to the greatest extent, while the synthesis of 7-methylguanosine and 2'-O-methyl nucleosides were inhibited to a lesser extent. Incubation of cells with 100 microM 3-deazaaristeromycin or with 10 microM 3-deazaadenosine and 50 microM homocysteine thiolactone produced little inhibition of mRNA synthesis, even though mRNA methylation was inhibited. In contrast, mRNA synthesis was greatly inhibited by treatment of cells with 100 microM 3-deazaadenosine and the inhibition of synthesis was not correlated with an inhibition of methylation.
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Kuo KC, Smith CE, Shi ZX, Agris PF, Gehrke CW. Quantitative measurement of mRNA cap 0 and cap 1 structures by high-performance liquid chromatography. JOURNAL OF CHROMATOGRAPHY 1986; 378:361-74. [PMID: 3733994 DOI: 10.1016/s0378-4347(00)80732-x] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Abstract
Viral and eukaryotic mRNA molecules have a unique 5'-end. The 5'-terminus consists of m7G(5')ppp(5')N'(m)pN''(m), which is termed a "cap" structure. The study of these cap structures has led to the development of many methods of identification and analysis. Many of the methods have been time-consuming or have not been able to distinguish between the different caps, and they are quantifiable only by employing radiolabels. This paper presents the use of reversed-phase high-performance liquid chromatography as a rapid and efficient tool for the separation, identification and quantitation of caps. An ion-exchange enrichment procedure was also developed for the isolation of cap 0 and cap 1 structures from unfractionated RNAs. The recoveries of different caps ranged from 83 to 99%, with a relative standard deviation range of 1.3-4.4%. In this method, caps were released from commercially obtained rabbit globin mRNA by nuclease P1 digestion. The products of digestion were treated with alkaline phosphatase and separated on an octadecylsilyl column using stepwise or gradient elution. Cap structures and any internal modified nucleosides were identified by their retention times and UV spectra relative to reference compounds. The amount of each cap 0 or cap 1 structure was determined by its UV absorbance relative to a known quantity of reference compound. This method allows the quantitation of 0.2 nmol or more of cap 0 and cap 1 structures. Total UV spectra can be obtained for 0.5 nmol or more of cap. This methodology permits investigations on viral and eukaryotic mRNA cap biosynthesis and turnover during viral transformation, differentiation, cap synthesis in the cell cycle, etc.
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Langberg S, Moss B. Post-transcriptional modifications of mRNA. Purification and characterization of cap I and cap II RNA (nucleoside-2'-)-methyltransferases from HeLa cells. J Biol Chem 1981. [DOI: 10.1016/s0021-9258(19)68740-5] [Citation(s) in RCA: 69] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022] Open
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Wallace JC, Wood WM, Edmonds M. 5'-Terminal cap structures of oligo(uridylic acid)-containing messenger ribonucleic acid from HeLa cells: comparison with other ribonucleic acid subpopulations. Biochemistry 1981; 20:5364-8. [PMID: 6170325 DOI: 10.1021/bi00522a002] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023]
Abstract
The 5'-terminal cap structures of 32P-labeled oligo(uridylic acid)-containing messenger ribonucleic acid [oligo(U+)mRNA] isolated from HeLa cell polyadenylated [poly(A+)] mRNA were analyzed and compared to those of the poly(A+) mRNA. A method employing P1 nuclease, alkaline phosphatase, and adsorption to activated charcoal showed that the types of cap core (m7 GpppXm) in oligo(U+) mRNA were essentially identical with those in poly(A+) mRNA. Analysis of RNase T2 digestion products of oligo(U+) mRNA demonstrated the presence of both cap 1 (m7GpppXmpYp) and cap 2 (m7GpppXmpYmpZp) in this subpopulation, confirming its cytoplasmic location. The base compositions of these two types of caps were different from each other and nonrandom but did not differ significantly between oligo(U+) and poly(A+) m RNA. The only observed difference between the mRNA populations was a higher ratio of cap 1 and cap 2 in the former. Possible implications of these findings for the relationship between oligo(U+) mRNA and poly(A+) mRNA are discussed.
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Cuming AC, Bennett J. Biosynthesis of the light-harvesting chlorophyll a/b protein. Control of messenger RNA activity by light. EUROPEAN JOURNAL OF BIOCHEMISTRY 1981; 118:71-80. [PMID: 6169525 DOI: 10.1111/j.1432-1033.1981.tb05487.x] [Citation(s) in RCA: 103] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/18/2023]
Abstract
1. Antibodies raised against the 26000-Mr polypeptides of the light-harvesting chlorophyll a/b proteins of pea leaves specifically immunoprecipitated two 32000-Mr polypeptides synthesized when pea leaf poly(A)-containing RNA was translated in vitro. On the basis of immunochemical relatedness and by comparison of their partial tryptic digestion products, the 32000-Mr products formed in vitro are identified as precursors to the authentic polypeptides of the light-harvesting chlorophyll a/b complex. 2. The specificity of the immunoprecipitation permitted the development of an assay for the cellular levels of translationally active light-harvesting protein mRNA in plants exposed to different light regimes. Low levels of the mRNAs were detectable in dark-grown plants. Exposure to continuous illumination caused these levels to increase by at least ten-fold and led to the appearance of large quantities of the light-harvesting chlorophyll a/b complex. In plants exposed to intermittent illumination (2 min of white light every 2 h for 2 days), the light-harvesting complex did not accumulate, although levels of mRNA specifying the polypeptides of the complex were high (50% of those in continuously illuminated plants). 3. Messenger RNAs encoding the light-harvesting proteins were detected in polysomes of intermittently illuminated leaves. These polysomes were active in a wheat-germ 100 000 X g supernatant "run-off" system, to form light-harvesting protein precursors, under conditions when only nascent polypeptide chains initiated in vivo were elongated and terminated. These results demonstrate that the inability of intermittently illuminated leaves to accumulate the light-harvesting proteins is not due to a selective inhibition of the translation of the corresponding mRNAs. 4. Intermittently illuminated leaves were labelled with [35S]methionine in darkness, and incorporation of radioisotope into the light-harvesting proteins and their precursors was assayed immunologically. No pool of untransported or unprocessed 32000-Mr precursor polypeptides could be detected in the soluble fraction (cytoplasm and stroma). However, low levels of the mature 26000-Mr polypeptides were detected in the membrane fraction. It is concluded that the newly synthesized light-harvesting chlorophyll a/b protein fail to accumulate in intermittently illuminated leaves because they undergo rapid turnover. The site of light-harvesting protein breakdown is probably the thylakoid membrane, and the cause of breakdown is probably the absence of chlorophyll a and chlorophyll b molecules that are required for eventual stabilization of the proteins within the photosynthetic membrane.
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Albers RJ, Coffin B, Rottman FM. Analysis of mRNA 5'-terminal cap structures and internal N6-methyladenosine by reversed-phase high-performance liquid chromatography. Anal Biochem 1981; 113:118-23. [PMID: 6115593 DOI: 10.1016/0003-2697(81)90053-1] [Citation(s) in RCA: 25] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023]
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Lane BG, Tumaitis-Kennedy TD. Comparative study of levels of secondary processing in bulk mRNA from dry and germinating wheat embryos. EUROPEAN JOURNAL OF BIOCHEMISTRY 1981; 114:457-63. [PMID: 6113140 DOI: 10.1111/j.1432-1033.1981.tb05167.x] [Citation(s) in RCA: 20] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/18/2023]
Abstract
There has been no previous study of levels of secondary processing in the template-active RNA of dry seeds and embryos. Such information is needed to evaluate the role of transcription in changing the cell-free translational capacity of bulk RNA during early imbibition of water by dry wheat embryos [J. Biol. Chem. 255, 5969-5970 (1980)]. Although it probably contains a higher proportion of "hidden breaks' than bulk mRNA from imbibing embryos, bulk mRNA in dry wheat embryos is also "capped' by 7-methylguanosine at 5' termini, devoid of unmethylated "caps', methylated internally (N6-methyladenosine) and polyadenylated at 3' termini. In contrast to other developing systems, there is no evidence that there are signal changes in levels of secondary processing in the bulk mRNA populations which support change in cell-free translational capacity of RNA 1-5 h postimbibition of dry wheat embryos. Change in the pattern of protein synthesis 5-24 h postimbibition also takes place without signal changes in levels of secondary processing in template-active RNA. The analytical data are evaluated and discussed in terms of difficulties allied with comparative analyses of poly(A)-rich RNA from dry and imbibing embryos, the former being refractory to, and the latter being most easily analyzed by, labeling in vivo.
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Thompson E, Lane B. Relation of protein synthesis in imbibing wheat embryos to the cell-free translational capacities of bulk mRNA from dry and imbibing embryos. J Biol Chem 1980. [DOI: 10.1016/s0021-9258(19)70725-x] [Citation(s) in RCA: 87] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022] Open
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Meyuhas O, Perry RP. Relationship between size, stability and abundance of the messenger RNA of mouse L cells. Cell 1979; 16:139-48. [PMID: 421268 DOI: 10.1016/0092-8674(79)90195-8] [Citation(s) in RCA: 59] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
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Pugh CS, Borchardt RT, Stone HO. Simultaneous assay for mRNA (guanine-7-)-methyltransferase and mRNA(2'-O-nucleoside)methyltransferase of purified vaccinia (WR) virions. Anal Biochem 1978; 88:504-12. [PMID: 697020 DOI: 10.1016/0003-2697(78)90450-5] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
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Monroy G, Spencer E, Hurwitz J. Purification of mRNA guanylyltransferase from vaccinia virions. J Biol Chem 1978. [DOI: 10.1016/s0021-9258(17)34745-2] [Citation(s) in RCA: 34] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023] Open
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Levis R, Penman S. 5'-terminal structures of poly(A)+ cytoplasmic messenger RNA and of poly(A)+ and poly(A)- heterogeneous nuclear RNA of cells of the dipteran Drosophila melanogaster. J Mol Biol 1978; 120:487-515. [PMID: 418182 DOI: 10.1016/0022-2836(78)90350-9] [Citation(s) in RCA: 77] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
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21
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Kaehler M, Coward J, Rottman F. In vivo inhibition of Novikoff cytoplasmic messenger RNA methylation by S-tubercidinylhomocysteine. Biochemistry 1977; 16:5770-5. [PMID: 201277 DOI: 10.1021/bi00645a019] [Citation(s) in RCA: 20] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
The analogue S-tubercidinylhomocysteine (STH) has been used to study the methylation of mRNA in vivo. Partial inhibition of cytoplasmic poly(A)-RNA methylation was observed using a level of inhibitor which still permitted cell growth. Characterization of the partially methylated mRNA indicated the presence of cap structures lacking 2'-O-methylnucleosides, m7GpppN', which are normally not found in mammalian mRNA. Inhibition of additional methylated sites in mRNA at the second 2'-O-methynucleoside, and at internal N6-methyladenosine was also observed Methylation of 7-methylguanosine was not affected under the conditions used in these experiments. The methylnucleoside composition of cap structures differed in STH-inhibited and uninhibited cells. These results indicate that a completely methylated cap is not required for transport of mRNA into the cytoplasm. Furthermore, it may now be possible to assess in vivo the sequential nature of mRNA methylation and its potential role in mRNA processing.
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Schibler U, Kelley DE, Perry RP. Comparison of methylated sequences in messenger RNA and heterogeneous nuclear RNA from mouse L cells. J Mol Biol 1977; 115:695-714. [PMID: 592376 DOI: 10.1016/0022-2836(77)90110-3] [Citation(s) in RCA: 202] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
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