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Akhlaq S, Panicker NG, Philip PS, Ali LM, Dudley JP, Rizvi TA, Mustafa F. A cis-Acting Element Downstream of the Mouse Mammary Tumor Virus Major Splice Donor Critical for RNA Elongation and Stability. J Mol Biol 2018; 430:4307-4324. [PMID: 30179605 DOI: 10.1016/j.jmb.2018.08.025] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2018] [Revised: 08/28/2018] [Accepted: 08/28/2018] [Indexed: 12/11/2022]
Abstract
BACKGROUND The mouse mammary tumor virus (MMTV) encodes a functional signal peptide, a cleavage product of envelope and Rem proteins. Signal peptide interacts with a 3' cis-acting RNA element, the Rem-responsive element (RmRE), to facilitate expression of both unspliced genomic (gRNA) and spliced mRNAs. An additional RmRE has been proposed at the 5' end of the genome, facilitating nuclear export of the unspliced gRNA, whereas the 3' RmRE could facilitate translation of all other mRNAs, including gRNA. RESULTS To address this hypothesis, a series of mutations were introduced into a 24-nt region found exclusively in the unspliced gRNA. Mutant clones using MMTV or human cytomegalovirus promoters were tested in both transient and stable transfections to determine their effect on gRNA nuclear export, stability, and translation. Nuclear export of the gRNA was affected only in a small mutant subset in stably transfected Jurkat T cells. Quantitative real-time RT-PCR of actinomycin D-treated cells expressing MMTV revealed that multiple mutants were severely compromised for RNA expression and stability. Both genomic and spliced nuclear RNAs were reduced, leading to abrogation of Gag and Env protein expressed from unspliced and spliced mRNAs, respectively. RT-PCRs with multiple primer pairs indicated failure to elongate genomic MMTV transcripts beyond ~500 nt compared to the wild type in a cell line-dependent manner. CONCLUSIONS MMTV contains a novel cis-acting element downstream of the major splice donor critical for facilitating MMTV gRNA elongation and stability. Presence of a mirror repeat within the element may represent important viral/host factor binding site(s) within MMTV gRNA.
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Affiliation(s)
- Shaima Akhlaq
- Department of Biochemistry, College of Medicine and Health Sciences, UAE University, Tawam Hospital Complex, P.O. Box 17666, Al Ain, United Arab Emirates.
| | - Neena G Panicker
- Department of Biochemistry, College of Medicine and Health Sciences, UAE University, Tawam Hospital Complex, P.O. Box 17666, Al Ain, United Arab Emirates.
| | - Pretty S Philip
- Department of Microbiology & Immunology, College of Medicine and Health Sciences, UAE University, Tawam Hospital Complex, P.O. Box 17666, Al Ain, United Arab Emirates.
| | - Lizna M Ali
- Department of Microbiology & Immunology, College of Medicine and Health Sciences, UAE University, Tawam Hospital Complex, P.O. Box 17666, Al Ain, United Arab Emirates.
| | - Jaquelin P Dudley
- LaMontagne Center for Infectious Diseases, The University of Texas at Austin, 100 East 24th Street, NHB 2.616, Austin, TX 78712, USA.
| | - Tahir A Rizvi
- Department of Microbiology & Immunology, College of Medicine and Health Sciences, UAE University, Tawam Hospital Complex, P.O. Box 17666, Al Ain, United Arab Emirates.
| | - Farah Mustafa
- Department of Biochemistry, College of Medicine and Health Sciences, UAE University, Tawam Hospital Complex, P.O. Box 17666, Al Ain, United Arab Emirates.
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Yang SS, Wang J, Li Z, Cui S, Liu W. The 5' Untranslated Region of the Capsid Protein 2 Gene of Mink Enteritis Virus Is Essential for Its Expression. J Virol 2018; 92:e00787-18. [PMID: 29976664 DOI: 10.1128/JVI.00787-18] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/07/2018] [Accepted: 06/14/2018] [Indexed: 12/15/2022] Open
Abstract
Mink enteritis virus (MEV), as a parvovirus, is among the smallest of the animal DNA viruses. The limited genome leads to multifunctional sequences and complex gene expression regulation. Here, we show that the expression of viral capsid protein 2 (VP2) of MEV requires its 5' untranslated regions (5' UTR) which promote VP2 gene expression at both transcriptional and translational levels. The expression of VP2 was inhibited in several common eukaryotic expression vectors. Our data showed that the 5' UTR of VP2 enhanced capsid gene transcription but not increased stability or promotes nucleocytoplasmic export of VP2 mRNA. Analysis of the functions of 5' UTR fragments showed that the proximal region (nucleotides [nt] 1 to 270; that is, positions +1 to +270 relative to the transcription initiation site, nt 2048 to 2317 of MEV-L) of 5' UTR of VP2 was necessary for VP2 transcription and also promoted the activity of P38 promoter. Unexpectedly, further analysis showed that deletion of the distal region (nt 271 to 653) of the 5' UTR of VP2 almost completely abolished VP2 translation in the presence of P38, whereas the transcription was still induced significantly. Furthermore, using a luciferase reporter bicistronic system, we identified that the 5' UTR had an internal ribosome entry site-like function which could be enhanced by NS1 via the site at nt 382 to 447. Mutation of the 5' UTR in the MEV full-length clones further showed that the 5' UTR was required for VP2 gene expression. Together, our data reveal an undiscovered function of 5' UTR of MEV VP2 in regulating viral gene expression.IMPORTANCE MEV, a parvovirus, causes acute enteritis in mink. In the present report, we describe an untranslated sequence-dependent mechanism by which MEV regulates capsid gene expression. Our results highlight the roles of untranslated sequences in regulating the transcriptional activity of P38 promoter and translation of capsid genes. These data also reveal the possibility of an unusual translation mechanism in capsid protein expression and the multiple functions of nonstructural protein. A better understanding of the gene expression regulation mechanism of this virus will help in the design of new vaccines and targets for antiviral agents against MEV.
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Zhang XM, Zha GM, Wang J, Wang XJ, Song S, Shu JC, Chu BB, Yang GY. Comparation of the effects of different 5'-untranslated regions (UTRs) on gene expression in HEK293 cells. Biotechnol Lett 2016; 38:2051-2057. [PMID: 27580891 DOI: 10.1007/s10529-016-2199-8] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/25/2016] [Accepted: 08/23/2016] [Indexed: 11/28/2022]
Abstract
OBJECTIVES To evaluate four 5'-UTRs on GFP expression in HEK293T cells. RESULTS The recombinant plasmids were constructed by restriction enzyme digestion, digestion and DNA sequencing. Quantitative real-time PCR and western blotting results showed that the transcription and translation level of PPRV-GFP mRNA was significantly lower than that of the other reporters. The transcription and translation level of ChEF1-GFP was the highest in HEK293T cells. CONCLUSIONS Different UTRs can significantly affect protein expression. Additionally, the findings also will be useful in biological applications that require tuning of gene expression and system optimization.
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Affiliation(s)
- Xue-Mei Zhang
- Key Laboratory of Animal Biochemistry and Nutrition, Ministry of Agriculture, Henan Agricultural University, Zhengzhou, Henan, People's Republic of China
| | - Guang-Ming Zha
- Key Laboratory of Animal Biochemistry and Nutrition, Ministry of Agriculture, Henan Agricultural University, Zhengzhou, Henan, People's Republic of China
| | - Jiang Wang
- Key Laboratory of Animal Biochemistry and Nutrition, Ministry of Agriculture, Henan Agricultural University, Zhengzhou, Henan, People's Republic of China
| | - Xin-Jian Wang
- Key Laboratory of Animal Biochemistry and Nutrition, Ministry of Agriculture, Henan Agricultural University, Zhengzhou, Henan, People's Republic of China
| | - Shuang Song
- Key Laboratory of Animal Biochemistry and Nutrition, Ministry of Agriculture, Henan Agricultural University, Zhengzhou, Henan, People's Republic of China
| | - Jing-Chao Shu
- Key Laboratory of Animal Biochemistry and Nutrition, Ministry of Agriculture, Henan Agricultural University, Zhengzhou, Henan, People's Republic of China
| | - Bei-Bei Chu
- Key Laboratory of Animal Biochemistry and Nutrition, Ministry of Agriculture, Henan Agricultural University, Zhengzhou, Henan, People's Republic of China
| | - Guo-Yu Yang
- Key Laboratory of Animal Biochemistry and Nutrition, Ministry of Agriculture, Henan Agricultural University, Zhengzhou, Henan, People's Republic of China. .,College of Animal Husbandary and Veterinary Science, Henan Agricultural University, Wenhua Road 95, Zhengzhou, 450002, People's Republic of China.
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Zhang G, Sharon D, Jovel J, Liu L, Wine E, Tahbaz N, Indik S, Mason A. Pericentriolar Targeting of the Mouse Mammary Tumor Virus GAG Protein. PLoS One 2015; 10:e0131515. [PMID: 26121257 PMCID: PMC4486188 DOI: 10.1371/journal.pone.0131515] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2015] [Accepted: 06/03/2015] [Indexed: 11/21/2022] Open
Abstract
The Gag protein of the mouse mammary tumor virus (MMTV) is the chief determinant of subcellular targeting. Electron microscopy studies show that MMTV Gag forms capsids within the cytoplasm and assembles as immature particles with MMTV RNA and the Y box binding protein-1, required for centrosome maturation. Other betaretroviruses, such as Mason-Pfizer monkey retrovirus (M-PMV), assemble adjacent to the pericentriolar region because of a cytoplasmic targeting and retention signal in the Matrix protein. Previous studies suggest that the MMTV Matrix protein may also harbor a similar cytoplasmic targeting and retention signal. Herein, we show that a substantial fraction of MMTV Gag localizes to the pericentriolar region. This was observed in HEK293T, HeLa human cell lines and the mouse derived NMuMG mammary gland cells. Moreover, MMTV capsids were observed adjacent to centrioles when expressed from plasmids encoding either MMTV Gag alone, Gag-Pro-Pol or full-length virus. We found that the cytoplasmic targeting and retention signal in the MMTV Matrix protein was sufficient for pericentriolar targeting, whereas mutation of the glutamine to alanine at position 56 (D56/A) resulted in plasma membrane localization, similar to previous observations from mutational studies of M-PMV Gag. Furthermore, transmission electron microscopy studies showed that MMTV capsids accumulate around centrioles suggesting that, similar to M-PMV, the pericentriolar region may be a site for MMTV assembly. Together, the data imply that MMTV Gag targets the pericentriolar region as a result of the MMTV cytoplasmic targeting and retention signal, possibly aided by the Y box protein-1 required for the assembly of centrosomal microtubules.
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Affiliation(s)
- Guangzhi Zhang
- Division of Gastroenterology, Department of Medicine, University of Alberta, Edmonton, Alberta, Canada
| | - David Sharon
- Division of Gastroenterology, Department of Medicine, University of Alberta, Edmonton, Alberta, Canada
| | - Juan Jovel
- Division of Gastroenterology, Department of Medicine, University of Alberta, Edmonton, Alberta, Canada
| | - Lei Liu
- Department of Pediatrics, University of Alberta, Edmonton, Alberta, Canada
| | - Eytan Wine
- Department of Pediatrics, University of Alberta, Edmonton, Alberta, Canada
| | - Nasser Tahbaz
- Department of Cell Biology, University of Alberta, Edmonton, Alberta, Canada
| | - Stanislav Indik
- Research Institute for Virology and Biomedicine, University of Veterinary Medicine Vienna, Vienna, A-1210, Austria
| | - Andrew Mason
- Division of Gastroenterology, Department of Medicine, University of Alberta, Edmonton, Alberta, Canada
- * E-mail:
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Naushad W, bin Rahat T, Gomez MK, Ashiq MT, Younas M, Sadia H. Detection and identification of mouse mammary tumor virus-like DNA sequences in blood and breast tissues of breast cancer patients. Tumour Biol 2014; 35:8077-86. [DOI: 10.1007/s13277-014-1972-3] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2014] [Accepted: 04/13/2014] [Indexed: 01/04/2023] Open
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Chulakasian S, Chang TJ, Tsai CH, Wong ML, Hsu WL. Translational enhancing activity in 5' UTR of peste des petits ruminants virus fusion gene. FEBS J 2013; 280:1237-48. [PMID: 23289829 DOI: 10.1111/febs.12115] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/26/2012] [Revised: 12/27/2012] [Accepted: 01/01/2013] [Indexed: 12/27/2022]
Abstract
The fusion gene of peste des petits ruminants virus (PPRV-F), a paramyxovirus, contains an unusual long 5' untranslated region (5' UTR) with a high GC content that is capable of folding into secondary structure proximally to the 5' cap. Sequence analysis further suggested that the proximal end of this UTR contains a nine-nucleotide sequence which could perfectly complement the 18S rRNA and might affect translation through mRNA-rRNA interaction. Based on these features, we examined the functional role of the proximal PPRV-F 5' UTR on translational efficiency compared with two other morbilliviruses. From reporter gene assays, PPRV-F 5' UTR functioned as a strong enhancer of translational efficiency independent of cell and gene specificity. Northern blot analysis of the accumulative RNA levels and mRNA stability suggested that elevated gene expression driven by PPRV-F 5' UTR was accompanied by an increased mRNA level and enhanced mRNA stability. Deletion analysis identified the complementary sequence and distal nucleotides necessary for the enhancing activity, and results suggest RNA structural conformation is important. Taken together, we conclude that the proximal PPRV-F 5' UTR functions as a translational enhancer by promoting translation efficiency and mRNA stability.
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Affiliation(s)
- Songkhla Chulakasian
- Department of Veterinary Medicine, College of Veterinary Medicine, National Chung Hsing University, Taichung, Taiwan
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Mustafa F, Al Amri D, Al Ali F, Al Sari N, Al Suwaidi S, Jayanth P, Philips PS, Rizvi TA. Sequences within both the 5' UTR and Gag are required for optimal in vivo packaging and propagation of mouse mammary tumor virus (MMTV) genomic RNA. PLoS One 2012; 7:e47088. [PMID: 23077548 DOI: 10.1371/journal.pone.0047088] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2012] [Accepted: 09/07/2012] [Indexed: 01/31/2023] Open
Abstract
Background This study mapped regions of genomic RNA (gRNA) important for packaging and propagation of mouse mammary tumor virus (MMTV). MMTV is a type B betaretrovirus which preassembles intracellularly, a phenomenon distinct from retroviruses that assemble the progeny virion at cell surface just before budding such as the type C human and feline immunodeficiency viruses (HIV and FIV). Studies of FIV and Mason-Pfizer monkey virus (MPMV), a type D betaretrovirus with similar intracellular virion assembly processes as MMTV, have shown that the 5′ untranslated region (5′ UTR) and 5′ end of gag constitute important packaging determinants for gRNA. Methodology Three series of MMTV transfer vectors containing incremental amounts of gag or 5′ UTR sequences, or incremental amounts of 5′ UTR in the presence of 400 nucleotides (nt) of gag were constructed to delineate the extent of 5′ sequences that may be involved in MMTV gRNA packaging. Real time PCR measured the packaging efficiency of these vector RNAs into MMTV particles generated by co-transfection of MMTV Gag/Pol, vesicular stomatitis virus envelope glycoprotein (VSV-G Env), and individual transfer vectors into human 293T cells. Transfer vector RNA propagation was monitored by measuring transduction of target HeLaT4 cells following infection with viral particles containing a hygromycin resistance gene expression cassette on the packaged RNA. Principal Findings MMTV requires the entire 5′ UTR and a minimum of ∼120 nucleotide (nt) at the 5′ end of gag for not only efficient gRNA packaging but also propagation of MMTV-based transfer vector RNAs. Vector RNAs without the entire 5′ UTR were defective for both efficient packaging and propagation into target cells. Conclusions/Significance These results reveal that the 5′ end of MMTV genome is critical for both gRNA packaging and propagation, unlike the recently delineated FIV and MPMV packaging determinants that have been shown to be of bipartite nature.
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