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Li X, Fan X, Yin X, Liu H, Yang Y. Alteration of N 6-methyladenosine epitranscriptome profile in unilateral ureteral obstructive nephropathy. Epigenomics 2020; 12:1157-1173. [PMID: 32543222 DOI: 10.2217/epi-2020-0126] [Citation(s) in RCA: 19] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022] Open
Abstract
Aim: To reveal the alterations of N6-methyladenosine (m6A) epitranscriptome profile in kidney after unilateral ureteral obstruction in mice. Materials & methods: Total renal m6A and expressions of methyltransferases and demethylases were detected by colorimetric quantification method, real-time PCR and western blot, respectively. Methylated RNA immunoprecipitation sequencing was performed to map epitranscriptome-wide m6A profile. Results: Total m6A levels were time-dependent decreased within 1 week, with the lowest level detected at day 7. A total of 823 differentially methylated transcripts in 507 genes were identified. Specifically, demethylated mRNAs selectively acted on multiple pathways, including TGF-β and WNT. Conclusion: m6A modification has a functional importance in renal interstitial fibrosis during obstructive nephropathy and might be a promising therapeutic target.
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Affiliation(s)
- Xueyan Li
- Department of Pediatric Urology, Shengjing Hospital of China Medical University, Shenyang, Liaoning 110004, PR China
| | - Xu Fan
- Department of Pediatric Urology, Shengjing Hospital of China Medical University, Shenyang, Liaoning 110004, PR China
| | - Xiaoming Yin
- Department of Pediatric Urology, Shengjing Hospital of China Medical University, Shenyang, Liaoning 110004, PR China
| | - Huajian Liu
- Department of Pediatric Urology, Shengjing Hospital of China Medical University, Shenyang, Liaoning 110004, PR China
| | - Yi Yang
- Department of Pediatric Urology, Shengjing Hospital of China Medical University, Shenyang, Liaoning 110004, PR China
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2
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Kang H, Zhang Z, Yu L, Li Y, Liang M, Zhou L. FTO reduces mitochondria and promotes hepatic fat accumulation through RNA demethylation. J Cell Biochem 2018; 119:5676-5685. [PMID: 29384213 DOI: 10.1002/jcb.26746] [Citation(s) in RCA: 92] [Impact Index Per Article: 15.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/21/2017] [Accepted: 01/25/2018] [Indexed: 12/27/2022]
Abstract
Fat mass and obesity-associated protein (FTO) is a RNA demethylase, whether FTO regulates fat metabolism through its demethylation is unclear. The results of this study confirmed that N6-methyladenosine (m6 A) is associated with fat accumulation both in vivo and in vitro. The data showed that FTO down-regulated m6 A levels, decreased mitochondrial content, and increased triglyceride (TG) deposition. However, an FTO (R316A) mutant lacking demethylation activity could not regulate mitochondria and TG content, indicating that FTO affects mitochondrial content and fat metabolism by modulating m6 A levels in hepatocytes. In addition, the regulatory roles of cycloleucine (methylation inhibitor) and betaine (methyl donor) could regulate m6 A levels and fat deposition. This work clarified that the demethylation function of FTO plays an essential role in the fat metabolism of hepatocytes and links the epigenetic modification of RNA with fat deposition, thereby providing a new target (m6 A) for regulation of hepatic fat metabolism.
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Affiliation(s)
- Huifang Kang
- State Key Laboratory for Conservation and Utilization of Subtropical Agro-bioresources, College of Animal Science and Technology, Guangxi University, Nanning, P.R. China
| | - Zhiwang Zhang
- State Key Laboratory for Conservation and Utilization of Subtropical Agro-bioresources, College of Animal Science and Technology, Guangxi University, Nanning, P.R. China
| | - Lin Yu
- State Key Laboratory for Conservation and Utilization of Subtropical Agro-bioresources, College of Animal Science and Technology, Guangxi University, Nanning, P.R. China
| | - Yixing Li
- State Key Laboratory for Conservation and Utilization of Subtropical Agro-bioresources, College of Animal Science and Technology, Guangxi University, Nanning, P.R. China
| | - Mingzhen Liang
- State Key Laboratory for Conservation and Utilization of Subtropical Agro-bioresources, College of Animal Science and Technology, Guangxi University, Nanning, P.R. China
| | - Lei Zhou
- State Key Laboratory for Conservation and Utilization of Subtropical Agro-bioresources, College of Animal Science and Technology, Guangxi University, Nanning, P.R. China
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3
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Wang Y, Zhao JC. Update: Mechanisms Underlying N 6-Methyladenosine Modification of Eukaryotic mRNA. Trends Genet 2016; 32:763-773. [PMID: 27793360 DOI: 10.1016/j.tig.2016.09.006] [Citation(s) in RCA: 38] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/05/2016] [Revised: 09/27/2016] [Accepted: 09/30/2016] [Indexed: 12/19/2022]
Abstract
Eukaryotic mRNA undergoes chemical modification both at the 5' cap and internally. Among internal modifications, N6-methyladensone (m6A), by far the most abundant, is present in all eukaryotes examined so far, including mammals, flies, plants, and yeast. m6A modification has an essential role in diverse biological processes. Over the past few years, our knowledge relevant to the establishment and function of this modification has grown rapidly. In this review, we focus on technologies that have facilitated m6A detection in mRNAs, the identification of m6A methylation enzymes and binding proteins, and potential functions of the modification at the molecular level.
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Affiliation(s)
- Yang Wang
- Tumor Initiation And Maintenance Program, Sanford Burnham Prebys Medical Discovery Institute, La Jolla, CA 92037, USA
| | - Jing Crystal Zhao
- Tumor Initiation And Maintenance Program, Sanford Burnham Prebys Medical Discovery Institute, La Jolla, CA 92037, USA.
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4
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Harcourt EM, Ehrenschwender T, Batista PJ, Chang HY, Kool ET. Identification of a selective polymerase enables detection of N(6)-methyladenosine in RNA. J Am Chem Soc 2013; 135:19079-82. [PMID: 24328136 DOI: 10.1021/ja4105792] [Citation(s) in RCA: 80] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
N(6)-methyladenosine (m(6)A) is the most abundant mRNA modification and has important links to human health. While recent studies have successfully identified thousands of mammalian RNA transcripts containing the modification, it is extremely difficult to identify the exact location of any specific m(6)A. Here we have identified a polymerase with reverse transcriptase activity (from Thermus thermophilus) that is selective by up to 18-fold for incorporation of thymidine opposite unmodified A over m(6)A. We show that the enzyme can be used to locate and quantify m(6)A in synthetic RNAs by analysis of pausing bands, and have used the enzyme in tandem with a nonselective polymerase to locate the presence and position of m(6)A in high-abundance cellular RNAs. By this approach we demonstrate that the long-undetermined position of m(6)A in mammalian 28S rRNA is nucleotide 4190.
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Affiliation(s)
- Emily M Harcourt
- Department of Chemistry, Stanford University , Stanford, California 94305, United States
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5
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Sibbritt T, Patel HR, Preiss T. Mapping and significance of the mRNA methylome. WILEY INTERDISCIPLINARY REVIEWS-RNA 2013; 4:397-422. [PMID: 23681756 DOI: 10.1002/wrna.1166] [Citation(s) in RCA: 76] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/01/2013] [Revised: 03/20/2013] [Accepted: 03/22/2013] [Indexed: 12/25/2022]
Abstract
Internal methylation of eukaryotic mRNAs in the form of N6-methyladenosine (m(6)A) and 5-methylcytidine (m(5)C) has long been known to exist, but progress in understanding its role was hampered by difficulties in identifying individual sites. This was recently overcome by high-throughput sequencing-based methods that mapped thousands of sites for both modifications throughout mammalian transcriptomes, with most sites found in mRNAs. The topology of m(6)A in mouse and human revealed both conserved and variable sites as well as plasticity in response to extracellular cues. Within mRNAs, m(5)C and m(6)A sites were relatively depleted in coding sequences and enriched in untranslated regions, suggesting functional interactions with post-transcriptional gene control. Finer distribution analyses and preexisting literature point toward roles in the regulation of mRNA splicing, translation, or decay, through an interplay with RNA-binding proteins and microRNAs. The methyltransferase (MTase) METTL3 'writes' m(6)A marks on mRNA, whereas the demethylase FTO can 'erase' them. The RNA:m(5)C MTases NSUN2 and TRDMT1 have roles in tRNA methylation but they also act on mRNA. Proper functioning of these enzymes is important in development and there are clear links to human disease. For instance, a common variant of FTO is a risk allele for obesity carried by 1 billion people worldwide and mutations cause a lethal syndrome with growth retardation and brain deficits. NSUN2 is linked to cancer and stem cell biology and mutations cause intellectual disability. In this review, we summarize the advances, open questions, and intriguing possibilities in this emerging field that might be called RNA modomics or epitranscriptomics.
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Affiliation(s)
- Tennille Sibbritt
- Genome Biology Department, The John Curtin School of Medical Research, The Australian National University, Canberra, ACT, Australia
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6
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Niu Y, Zhao X, Wu YS, Li MM, Wang XJ, Yang YG. N6-methyl-adenosine (m6A) in RNA: an old modification with a novel epigenetic function. GENOMICS PROTEOMICS & BIOINFORMATICS 2012; 11:8-17. [PMID: 23453015 PMCID: PMC4357660 DOI: 10.1016/j.gpb.2012.12.002] [Citation(s) in RCA: 318] [Impact Index Per Article: 26.5] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 11/26/2012] [Revised: 12/10/2012] [Accepted: 12/11/2012] [Indexed: 12/02/2022]
Abstract
N6-methyl-adenosine (m6A) is one of the most common and abundant modifications on RNA molecules present in eukaryotes. However, the biological significance of m6A methylation remains largely unknown. Several independent lines of evidence suggest that the dynamic regulation of m6A may have a profound impact on gene expression regulation. The m6A modification is catalyzed by an unidentified methyltransferase complex containing at least one subunit methyltransferase like 3 (METTL3). m6A modification on messenger RNAs (mRNAs) mainly occurs in the exonic regions and 3′-untranslated region (3′-UTR) as revealed by high-throughput m6A-seq. One significant advance in m6A research is the recent discovery of the first two m6A RNA demethylases fat mass and obesity-associated (FTO) gene and ALKBH5, which catalyze m6A demethylation in an α-ketoglutarate (α-KG)- and Fe2+-dependent manner. Recent studies in model organisms demonstrate that METTL3, FTO and ALKBH5 play important roles in many biological processes, ranging from development and metabolism to fertility. Moreover, perturbation of activities of these enzymes leads to the disturbed expression of thousands of genes at the cellular level, implicating a regulatory role of m6A in RNA metabolism. Given the vital roles of DNA and histone methylations in epigenetic regulation of basic life processes in mammals, the dynamic and reversible chemical m6A modification on RNA may also serve as a novel epigenetic marker of profound biological significances.
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Affiliation(s)
- Yamei Niu
- Disease Genomics and Individualized Medicine Laboratory, Beijing Institute of Genomics, Chinese Academy of Sciences, Beijing 100101, China
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7
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Narayan P, Rottman FM. Methylation of mRNA. ADVANCES IN ENZYMOLOGY AND RELATED AREAS OF MOLECULAR BIOLOGY 2006; 65:255-85. [PMID: 1315118 DOI: 10.1002/9780470123119.ch7] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Affiliation(s)
- P Narayan
- Department of Molecular Biology and Microbiology, Case Western Reserve University, School of Medicine, Cleveland, Ohio
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8
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The biosynthesis and functional roles of methylated nucleosides in eukaryotic mRNA. FINE-TUNING OF RNA FUNCTIONS BY MODIFICATION AND EDITING 2005. [DOI: 10.1007/b106365] [Citation(s) in RCA: 51] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
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9
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Clancy MJ, Shambaugh ME, Timpte CS, Bokar JA. Induction of sporulation in Saccharomyces cerevisiae leads to the formation of N6-methyladenosine in mRNA: a potential mechanism for the activity of the IME4 gene. Nucleic Acids Res 2002; 30:4509-18. [PMID: 12384598 PMCID: PMC137137 DOI: 10.1093/nar/gkf573] [Citation(s) in RCA: 227] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
N6-methyladenosine (m6A) is present at internal sites in mRNA isolated from all higher eukaryotes, but has not previously been detected in the mRNA of the yeast Saccharomyces cerevisiae. This nucleoside modification occurs only in a sequence- specific context that appears to be conserved across diverse species. The function of this modification is not fully established, but there is some indirect evidence that m6A may play a role in the efficiency of mRNA splicing, transport or translation. The S.cerevisiae gene IME4, which is important for induction of sporulation, is very similar to the human gene MT-A70, which has been shown to be a critical subunit of the human mRNA [N6-adenosine]-methyltransferase. This observation led to the hypothesis that yeast sporulation may be dependent upon methylation of yeast mRNA, mediated by Ime4p. In this study we show that induction of sporulation leads to the appearance of low levels of m6A in yeast mRNA and that this modification requires IME4. Moreover, single amino acid substitutions in the putative catalytic residues of Ime4p lead to severe sporulation defects in a strain whose sporulation ability is completely dependent on this protein. Collectively, these data suggest very strongly that the activation of sporulation by Ime4p is the result of its proposed methyltransferase activity and provide the most direct evidence to date of a physiologic role of m6A in a gene regulatory pathway.
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Affiliation(s)
- Mary J Clancy
- Department of Biological Sciences, University of New Orleans, New Orleans, LA 70148, USA
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10
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Leach RA, Tuck MT. Methionine depletion induces transcription of the mRNA (N6-adenosine)methyltransferase. Int J Biochem Cell Biol 2001; 33:1116-28. [PMID: 11551827 DOI: 10.1016/s1357-2725(01)00072-3] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
This study examines the genetic expression of the S-adenosyl-L-methionine binding subunit of the mRNA (N6-adenosine)methyltransferase (MT-A70) in cultured cells under conditions known to affect transmethylation reactions. Methionine dependence, disrupted methionine metabolism, and increased transmethylation reactions are all phenotypes characteristic of cancer cells. The results show that both methionine depletion and inhibition of S-adenosyl-L-methionine formation can induce up to a four-fold increase in transcription of this S-adenosyl-L-methionine binding subunit. The two splice-variant mRNAs produced from the MT-A70 gene are transcribed at different rates depending on the level of S-adenosyl-L-methionine inhibition. This result may reflect differing Km values toward the substrate for the different enzyme isoforms. 3-Deazaadenosine, an inhibitor known to block certain mRNA transmethylations, was shown to have no effect on MT-A70 gene expression. This result indicates that the control of MT-A70 gene expression is directly related to methionine availability and the subsequent synthesis of S-adenosyl-L-methionine.
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Affiliation(s)
- R A Leach
- Department of Biological Sciences, Ohio University, Athens, OH 45701, USA
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11
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Narayan P, Ludwiczak RL, Goodwin EC, Rottman FM. Context effects on N6-adenosine methylation sites in prolactin mRNA. Nucleic Acids Res 1994; 22:419-26. [PMID: 8127679 PMCID: PMC523598 DOI: 10.1093/nar/22.3.419] [Citation(s) in RCA: 58] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023] Open
Abstract
The methylation of internal adenosine residues in mRNA only occurs within GAC or AAC sequences. Although both of these sequence motifs are utilized, a general preference has been noted for the extended sequence RGACU. Not all RGACU sequences in an mRNA are methylated and the mechanisms that govern the selection of methylation sites in mRNA remain unclear. To address this problem we have examined the methylation of transcripts containing sequences of a natural mRNA, namely, bovine prolactin mRNA. In this mRNA, a specific AGACU sequence in the 3' untranslated region is the predominant site of methylation both in vivo and in vitro. The degree to which N6-adenosine methyltransferase recognizes the sequence context of the consensus methylation site was explored by mutational analysis of the nucleotides adjacent to the core sequence as well as the extended regions in which the core element was found. Our results indicate that efficient methylation depends on the extended five nucleotide consensus sequence but is strongly influenced by the context in which the consensus sequence occurs within the overall mRNA molecule. Furthermore, consensus methylation sites present in an RNA duplex are not recognized by the methyltransferase.
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Affiliation(s)
- P Narayan
- Department of Molecular Biology and Microbiology, Case Western Reserve University, Cleveland, OH 44106
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12
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Abstract
N6-methyladenosine (m6A) residues occur at internal positions in most cellular and viral RNAs; both heterogeneous nuclear RNA and mRNA are involved. This modification arises by enzymatic transfer of a methyl group from S-adenosylmethionine to the central adenosine residue in the canonical sequence G/AAC. Thus far, m6A has been mapped to specific locations in eucaryotic mRNA and viral genomic RNA. We have now examined an intron-specific sequence of a modified bovine prolactin precursor RNA for the presence of this methylated nucleotide by using both transfected-cell systems and a cell-free system capable of methylating mRNA transcripts in vitro. The results indicate the final intron-specific sequence (intron D) of a prolactin RNA molecule does indeed possess m6A residues. When mapped to specific T1 oligonucleotides, the predominant site of methylation was found to be within the consensus sequence AGm6ACU. The level of m6A at this site is nonstoichiometric; approximately 24% of the molecules are modified in vivo. Methylation was detected at markedly reduced levels at other consensus sites within the intron but not in T1 oligonucleotides which do not contain either AAC or GAC consensus sequences. In an attempt to correlate mRNA methylation with processing, stably transfected CHO cells expressing augmented levels of bovine prolactin were treated with neplanocin A, an inhibitor of methylation. Under these conditions, the relative steady-state levels of the intron-containing nuclear precursor increased four to six times that found in control cells.
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13
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Carroll SM, Narayan P, Rottman FM. N6-methyladenosine residues in an intron-specific region of prolactin pre-mRNA. Mol Cell Biol 1990; 10:4456-65. [PMID: 2388614 PMCID: PMC361031 DOI: 10.1128/mcb.10.9.4456-4465.1990] [Citation(s) in RCA: 45] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
Abstract
N6-methyladenosine (m6A) residues occur at internal positions in most cellular and viral RNAs; both heterogeneous nuclear RNA and mRNA are involved. This modification arises by enzymatic transfer of a methyl group from S-adenosylmethionine to the central adenosine residue in the canonical sequence G/AAC. Thus far, m6A has been mapped to specific locations in eucaryotic mRNA and viral genomic RNA. We have now examined an intron-specific sequence of a modified bovine prolactin precursor RNA for the presence of this methylated nucleotide by using both transfected-cell systems and a cell-free system capable of methylating mRNA transcripts in vitro. The results indicate the final intron-specific sequence (intron D) of a prolactin RNA molecule does indeed possess m6A residues. When mapped to specific T1 oligonucleotides, the predominant site of methylation was found to be within the consensus sequence AGm6ACU. The level of m6A at this site is nonstoichiometric; approximately 24% of the molecules are modified in vivo. Methylation was detected at markedly reduced levels at other consensus sites within the intron but not in T1 oligonucleotides which do not contain either AAC or GAC consensus sequences. In an attempt to correlate mRNA methylation with processing, stably transfected CHO cells expressing augmented levels of bovine prolactin were treated with neplanocin A, an inhibitor of methylation. Under these conditions, the relative steady-state levels of the intron-containing nuclear precursor increased four to six times that found in control cells.
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Affiliation(s)
- S M Carroll
- Department of Molecular Biology and Microbiology, Case Western Reserve University, Cleveland, Ohio 44106
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14
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Prince DL, Kotin RM, Dubin DT. Evidence that the methylation inhibitor cycloleucine causes accumulation of a discrete ribosomal RNA precursor in hamster mitochondria. Mol Biol Rep 1986; 11:51-5. [PMID: 3633018 DOI: 10.1007/bf00417596] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Abstract
A novel RNA fraction, 'Cy RNA,' that accumulates in mitochondria when hamster cells are treated with the methylation inhibitor cycloleucine, has been characterized by high resolution acrylamide gel electrophoresis and DNA-RNA hybridization. Cy RNA ran in gels as a discrete band, with an apparent chain length of 2 600. It hybridized specifically to restriction fragments containing genes for the mitochondrial ribosomal RNAs. We infer that Cy RNA is a discrete polycistronic ribosomal RNA precursor transcript, whose processing is dependent on normal methylation.
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15
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Finkel D, Groner Y. Methylations of adenosine residues (m6A) in pre-mRNA are important for formation of late simian virus 40 mRNAs. Virology 1983; 131:409-25. [PMID: 6318439 DOI: 10.1016/0042-6822(83)90508-1] [Citation(s) in RCA: 82] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
Abstract
Cycloleucine, a competitive inhibitor of methionine transferase was used to generate in vivo partially methylated mRNA in SV40-infected BSC-1 cells. Cycloleucine at 0.5 mg/ml causes more than a 30% decrease in internal m6As of late SV40 mRNA with only minor effect on the dimethyladenosine of the 5' caps m7GpppmAm. After treatment with 2 and 5 mg/ml of cycloleucine, internal m6As were reduced by 10- and 100-fold, respectively. The inhibition of BSC-1 mRNA methylations paralleled that observed for late SV40 mRNAs. In cells exposed to 2 mg/ml cycloleucine production of late SV40 mRNA was inhibited by 80% whereas the amount of SV40 nuclear RNA was only slightly reduced. Size fractionation of SV40 nuclear RNA from cycloleucine-treated cells revealed a loss of SV40 19 S RNA with a corresponding increase of fragmented RNA sedimenting between 11 to 5 S, so that the total amount of SV40 RNA in the nucleus was almost unchanged. Analysis of viral transcription complexes from cells treated with cycloleucine indicated that SV40 transcription was not affected by cycloleucine. SV40-transformed cells, in contrast to BSC-1 cells, were able to process and transport undermethylated RNA. When transformed cells were treated with 2 mg/ml cycloleucine no changes in quantities or size of cytoplasmic and nuclear RNA were detected. The data argues for a role of internal m6A moieties in modulating the processing-linked transport of mRNA from the nucleus to the cytoplasm of nontransformed cells. Transformed cells may escape these controls due to structural alterations in their perinuclear regions.
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16
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Stoltzfus CM, Dane RW. Accumulation of spliced avian retrovirus mRNA is inhibited in S-adenosylmethionine-depleted chicken embryo fibroblasts. J Virol 1982; 42:918-31. [PMID: 6285005 PMCID: PMC256926 DOI: 10.1128/jvi.42.3.918-931.1982] [Citation(s) in RCA: 75] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023] Open
Abstract
The synthesis and processing of B77 avian sarcoma virus RNA in infected chicken embryo fibroblasts was followed in the presence and absence of cycloleucine, a competitive inhibitor of the synthesis of S-adenosylmethionine and thus an inhibitor of RNA methylations. An increase in the steady-state levels of genome-length RNA and a decrease in the steady-state levels of subgenomic RNA molecules were obtained in the S-adenosylmethionine-depleted avian sarcoma virus-infected cells after 24 h of treatment with the inhibitor. The total number of virus-specific RNA molecules per cell, however, remained relatively constant under either condition. The production of newly synthesized virus-specific RNA in cycloleucine-treated and untreated cells infected with a transformation-defective strain of B77 avian sarcoma virus was followed as a function of [(3)H]uridine labeling time. The accumulation of radioactive genome-length 8.4-kilobase (kb) RNA continued in cycloleucine-treated cells, and virus particle production proceeded at normal rates as previously shown by incorporation of labeled nucleoside precursors or amino acids. In contrast, newly synthesized 3.5-kb subgenomic mRNA, the putative mRNA for the envelope protein precursor, failed to accumulate in the treated cells. The extent of the inhibition in the appearance of the radioactive 3.5-kb RNA was correlated with the extent of the inhibition of viral genomic and cellular mRNA methylations and was a function of the cycloleucine concentration. Under conditions in which the accumulation of 3.5-kb envelope protein mRNA was blocked by the cycloleucine treatment, there were significant increases in the rate of synthesis of the polypeptide products of the genome-length RNA, the precursors to the non-glycosylated gag proteins (Pr76(gag)), and the reverse transcriptase (Pr 180(gag pol)) relative to the rate of synthesis of the envelope protein precursor (gPr 92(env)). These results suggest that there is an S-adenosylmethionine requirement for the splicing, but not for the synthesis, packaging, or messenger function, of avian retrovirus genome-length RNA. Possible reasons for this requirement are discussed.
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17
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Goswami BB, Crea R, Van Boom JH, Sharma OK. 2'-5'-Linked oligo(adenylic acid) and its analogs. A new class of inhibitors of mRNA methylation. J Biol Chem 1982. [DOI: 10.1016/s0021-9258(18)34510-1] [Citation(s) in RCA: 23] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022] Open
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18
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Masatomo M, Yasuhito T, Osamu D, Akihiko N, Masahiro N, Yuzuru A. Two types of inhibitor of phospholipid methylation in MOPC-31C cells with modified membrane phospholipids. ACTA ACUST UNITED AC 1981. [DOI: 10.1016/0005-2760(81)90117-x] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
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19
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Moyer SA. Alteration of the 5' terminal caps of the mRNAs of vesicular stomatitis virus by cycloleucine in vivo. Virology 1981; 112:157-68. [PMID: 6264679 DOI: 10.1016/0042-6822(81)90621-8] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
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20
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Katinakis PK, Burdon RH. The metabolic behaviour of nuclear and cytoplasmic non-polyadenylated RNAs with an affinity for poly(adenylic acid) from Friend murine leukaemia cells. BIOCHIMICA ET BIOPHYSICA ACTA 1981; 653:39-51. [PMID: 6164396 DOI: 10.1016/0005-2787(81)90102-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/18/2023]
Abstract
Using poly(A)-Sepharose and poly(U)-Sepharose affinity chromatography, various classes of nuclear RNA can be distinguished in Friend leukaemia cells. One of these contains a poly(A) tract (poly(A)+-RNA) and another lacks a poly(A) tract but has an affinity for poly(A)-Sepharose (poly(A)-u+-RNA). The stability of these two particular nuclear RNA classes was examined by using a 'pulse-chase' technique involving D-glucosamine treatment. Nuclear poly(A)-u+-RNA was found to decay as a single component with a half-life of about 12 min. In contrast, nuclear poly(A)+-RNA appears to consist of at least two distinct metabolic components with half-lives of about 22 min and 120 min. Furthermore, poly(A)-u+-RNA is transported from the nuclei much more rapidly than the poly(A)+-RNA. The 'pulse-chase' approach also allowed a quantitative estimate to be made of the conversion of nuclear poly(A)+-RNA and poly(A)-u+-RNA to cytoplasmic poly(A)-RNA and poly(A)-u+-RNA.
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21
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Katinakis PK, Burdon RH. Isolation and characterisation of a non-polyadenylated mRNA species with an affinity for poly(adenylic acid) from Friend leukaemia cells. BIOCHIMICA ET BIOPHYSICA ACTA 1981; 653:27-38. [PMID: 6112016 DOI: 10.1016/0005-2787(81)90101-5] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/18/2023]
Abstract
Utilizing the technique of poly(A)-Sepharose affinity chromatography, it is possible to isolate a novel class of RNA molecules from polysomes of Friend leukaemia cells. These RNA species display messenger RNA-like behaviour. They are released from polysomes on treatment with EDTA and are able to direct polypeptide synthesis in a cell-free protein synthesising system. They appear to be distinct from the polyadenylated mRNAs, as judged by their lack of a 3'-terminal poly(A) tract, by their different size distribution, by their unusual base composition, by the presence of a possible 'uridylate rich' region towards their 3'-end, by their low sequence homology to polyadenylated mRNAs and by the difference in at least some of their translation products.
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Ahl R. Effect of inhibitors of methylation on early and late interferon synthesis in bovine kidney cell cultures. JOURNAL OF INTERFERON RESEARCH 1981; 1:203-18. [PMID: 6180052 DOI: 10.1089/jir.1981.1.203] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/18/2023]
Abstract
In virus infected bovine kidney cell cultures mainly late interferon is produced starting at about 4 hr after infection. Poly rI:poly rC induced cells as well as interferon pretreated virus infected cells produce early interferon starting immediately after induction. In infected cells the proportion of early interferon increases with time of interferon pretreatment, while late interferon is decreasing. Production of late interferon is selectively inhibited by cycloleucine, an inhibitor of S-adenosylmethionine (SAM) biosynthesis, whereas early interferon synthesis is not affected by the drug. Likewise, late interferon production is reduced much stronger than early interferon production by a combination of adenosine, L-homocysteine thiolactone, and erythro-9[3-(2-hydroxynonyl)]-adenine (EHNA) inducing in cells an accumulation of S-adenosylhomocysteine which inhibits SAM mediated methylation reactions. Inhibition of late interferon synthesis by cycloleucine is time and dose dependent and partially reversible. Cycloheximide equally blocks both early and late interferon production. Inhibition of incorporation of methyl groups into cellular RNA by the methylation inhibitors used is demonstrated by labeling with [methyl-3H] methionine and 3H-uridine. The results indicate that the synthesis of functional mRNA for early and late interferon is differentially sensitive to inhibition of methylation. The data suggest that, if early and late interferon is coded by the same structural gene, two different pathways are available for the cell to synthesize one species of mRNA.
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Caboche M, La Bonnardiere C. Vesicular stomatitis virus mRNA methylation in vivo: effect of cycloleucine, an inhibitor of S-adenosylmethionine biosynthesis, on viral transcription and translation. Virology 1979; 93:547-57. [PMID: 222056 DOI: 10.1016/0042-6822(79)90257-5] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
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