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Mustafa F, Vivet-Boudou V, Jabeen A, Ali LM, Kalloush RM, Marquet R, Rizvi TA. The bifurcated stem loop 4 (SL4) is crucial for efficient packaging of mouse mammary tumor virus (MMTV) genomic RNA. RNA Biol 2018; 15:1047-1059. [PMID: 29929424 PMCID: PMC6161677 DOI: 10.1080/15476286.2018.1486661] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
Packaging the mouse mammary tumor virus (MMTV) genomic RNA (gRNA) requires the entire 5' untranslated region (UTR) in conjunction with the first 120 nucleotides of the gag gene. This region includes several palindromic (pal) sequence(s) and stable stem loops (SLs). Among these, stem loop 4 (SL4) adopts a bifurcated structure consisting of three stems, two apical loops, and an internal loop. Pal II, located in one of the apical loops, mediates gRNA dimerization, a process intricately linked to packaging. We thus hypothesized that the bifurcated SL4 structure could constitute the major gRNA packaging determinant. To test this hypothesis, the two apical loops and the flanking sequences forming the bifurcated SL4 were individually mutated. These mutations all had deleterious effects on gRNA packaging and propagation. Next, single and compensatory mutants were designed to destabilize then recreate the bifurcated SL4 structure. A structure-function analysis using bioinformatics predictions and RNA chemical probing revealed that mutations that led to the loss of the SL4 bifurcated structure abrogated RNA packaging and propagation, while compensatory mutations that recreated the native SL4 structure restored RNA packaging and propagation to wild type levels. Altogether, our results demonstrate that SL4 constitutes the principal packaging determinant of MMTV gRNA. Our findings further suggest that SL4 acts as a structural switch that can not only differentiate between RNA for translation versus packaging/dimerization, but its location also allows differentiation between spliced and unspliced RNAs during gRNA encapsidation.
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Affiliation(s)
- Farah Mustafa
- a Department of Biochemistry , College of Medicine and Health Sciences, United Arab Emirates University , Al Ain , UAE
| | - Valérie Vivet-Boudou
- b Université de Strasbourg , CNRS, Architecture et Réactivité de l'ARN , Strasbourg , France
| | - Ayesha Jabeen
- c Department of Microbiology & Immunology , College of Medicine and Health Sciences, United Arab Emirates University , Al Ain , UAE
| | - Lizna M Ali
- c Department of Microbiology & Immunology , College of Medicine and Health Sciences, United Arab Emirates University , Al Ain , UAE
| | - Rawan M Kalloush
- c Department of Microbiology & Immunology , College of Medicine and Health Sciences, United Arab Emirates University , Al Ain , UAE
| | - Roland Marquet
- b Université de Strasbourg , CNRS, Architecture et Réactivité de l'ARN , Strasbourg , France
| | - Tahir A Rizvi
- c Department of Microbiology & Immunology , College of Medicine and Health Sciences, United Arab Emirates University , Al Ain , UAE
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Cross- and Co-Packaging of Retroviral RNAs and Their Consequences. Viruses 2016; 8:v8100276. [PMID: 27727192 PMCID: PMC5086612 DOI: 10.3390/v8100276] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/11/2016] [Revised: 10/03/2016] [Accepted: 10/03/2016] [Indexed: 12/23/2022] Open
Abstract
Retroviruses belong to the family Retroviridae and are ribonucleoprotein (RNP) particles that contain a dimeric RNA genome. Retroviral particle assembly is a complex process, and how the virus is able to recognize and specifically capture the genomic RNA (gRNA) among millions of other cellular and spliced retroviral RNAs has been the subject of extensive investigation over the last two decades. The specificity towards RNA packaging requires higher order interactions of the retroviral gRNA with the structural Gag proteins. Moreover, several retroviruses have been shown to have the ability to cross-/co-package gRNA from other retroviruses, despite little sequence homology. This review will compare the determinants of gRNA encapsidation among different retroviruses, followed by an examination of our current understanding of the interaction between diverse viral genomes and heterologous proteins, leading to their cross-/co-packaging. Retroviruses are well-known serious animal and human pathogens, and such a cross-/co-packaging phenomenon could result in the generation of novel viral variants with unknown pathogenic potential. At the same time, however, an enhanced understanding of the molecular mechanisms involved in these specific interactions makes retroviruses an attractive target for anti-viral drugs, vaccines, and vectors for human gene therapy.
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Kalloush RM, Vivet-Boudou V, Ali LM, Mustafa F, Marquet R, Rizvi TA. Packaging of Mason-Pfizer monkey virus (MPMV) genomic RNA depends upon conserved long-range interactions (LRIs) between U5 and gag sequences. RNA (NEW YORK, N.Y.) 2016; 22:905-919. [PMID: 27095024 PMCID: PMC4878616 DOI: 10.1261/rna.055731.115] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 12/20/2015] [Accepted: 03/09/2016] [Indexed: 06/05/2023]
Abstract
MPMV has great potential for development as a vector for gene therapy. In this respect, precisely defining the sequences and structural motifs that are important for dimerization and packaging of its genomic RNA (gRNA) are of utmost importance. A distinguishing feature of the MPMV gRNA packaging signal is two phylogenetically conserved long-range interactions (LRIs) between U5 and gag complementary sequences, LRI-I and LRI-II. To test their biological significance in the MPMV life cycle, we introduced mutations into these structural motifs and tested their effects on MPMV gRNA packaging and propagation. Furthermore, we probed the structure of key mutants using SHAPE (selective 2'hydroxyl acylation analyzed by primer extension). Disrupting base-pairing of the LRIs affected gRNA packaging and propagation, demonstrating their significance to the MPMV life cycle. A double mutant restoring a heterologous LRI-I was fully functional, whereas a similar LRI-II mutant failed to restore gRNA packaging and propagation. These results demonstrate that while LRI-I acts at the structural level, maintaining base-pairing is not sufficient for LRI-II function. In addition, in vitro RNA dimerization assays indicated that the loss of RNA packaging in LRI mutants could not be attributed to the defects in dimerization. Our findings suggest that U5-gag LRIs play an important architectural role in maintaining the structure of the 5' region of the MPMV gRNA, expanding the crucial role of LRIs to the nonlentiviral group of retroviruses.
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Affiliation(s)
- Rawan M Kalloush
- Department of Microbiology and Immunology, College of Medicine and Health Sciences, United Arab Emirates University, Al Ain, United Arab Emirates
| | - Valérie Vivet-Boudou
- Architecture et Réactivité de l'ARN, CNRS, IBMC, Université de Strasbourg, 67084 Strasbourg cedex, France
| | - Lizna M Ali
- Department of Microbiology and Immunology, College of Medicine and Health Sciences, United Arab Emirates University, Al Ain, United Arab Emirates
| | - Farah Mustafa
- Department of Biochemistry, College of Medicine and Health Sciences, United Arab Emirates University, Al Ain, United Arab Emirates
| | - Roland Marquet
- Architecture et Réactivité de l'ARN, CNRS, IBMC, Université de Strasbourg, 67084 Strasbourg cedex, France
| | - Tahir A Rizvi
- Department of Microbiology and Immunology, College of Medicine and Health Sciences, United Arab Emirates University, Al Ain, United Arab Emirates
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Aktar SJ, Vivet-Boudou V, Ali LM, Jabeen A, Kalloush RM, Richer D, Mustafa F, Marquet R, Rizvi TA. Structural basis of genomic RNA (gRNA) dimerization and packaging determinants of mouse mammary tumor virus (MMTV). Retrovirology 2014; 11:96. [PMID: 25394412 PMCID: PMC4264320 DOI: 10.1186/s12977-014-0096-6] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/08/2014] [Accepted: 10/23/2014] [Indexed: 11/13/2022] Open
Abstract
Background One of the hallmarks of retroviral life cycle is the efficient and specific packaging of two copies of retroviral gRNA in the form of a non-covalent RNA dimer by the assembling virions. It is becoming increasingly clear that the process of dimerization is closely linked with gRNA packaging, and in some retroviruses, the latter depends on the former. Earlier mutational analysis of the 5’ end of the MMTV genome indicated that MMTV gRNA packaging determinants comprise sequences both within the 5’ untranslated region (5’ UTR) and the beginning of gag. Results The RNA secondary structure of MMTV gRNA packaging sequences was elucidated employing selective 2’hydroxyl acylation analyzed by primer extension (SHAPE). SHAPE analyses revealed the presence of a U5/Gag long-range interaction (U5/Gag LRI), not predicted by minimum free-energy structure predictions that potentially stabilizes the global structure of this region. Structure conservation along with base-pair covariations between different strains of MMTV further supported the SHAPE-validated model. The 5’ region of the MMTV gRNA contains multiple palindromic (pal) sequences that could initiate intermolecular interaction during RNA dimerization. In vitro RNA dimerization, SHAPE analysis, and structure prediction approaches on a series of pal mutants revealed that MMTV RNA utilizes a palindromic point of contact to initiate intermolecular interactions between two gRNAs, leading to dimerization. This contact point resides within pal II (5’ CGGCCG 3’) at the 5’ UTR and contains a canonical “GC” dyad and therefore likely constitutes the MMTV RNA dimerization initiation site (DIS). Further analyses of these pal mutants employing in vivo genetic approaches indicate that pal II, as well as pal sequences located in the primer binding site (PBS) are both required for efficient MMTV gRNA packaging. Conclusions Employing structural prediction, biochemical, and genetic approaches, we show that pal II functions as a primary point of contact between two MMTV RNAs, leading to gRNA dimerization and its subsequent encapsidation into the assembling virus particles. The results presented here enhance our understanding of the MMTV gRNA dimerization and packaging processes and the role of structural motifs with respect to RNA-RNA and possibly RNA-protein interactions that might be taking place during MMTV life cycle. Electronic supplementary material The online version of this article (doi:10.1186/s12977-014-0096-6) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Suriya J Aktar
- Department of Microbiology & Immunology, College of Medicine and Health Sciences, United Arab Emirates University, P.O. Box 17666, Al Ain, United Arab Emirates.
| | - Valérie Vivet-Boudou
- Architecture et Réactivité de l'ARN, CNRS, IBMC, Université de Strasbourg, 15 rue René Descartes, 67084, Strasbourg cedex, France.
| | - Lizna M Ali
- Department of Microbiology & Immunology, College of Medicine and Health Sciences, United Arab Emirates University, P.O. Box 17666, Al Ain, United Arab Emirates.
| | - Ayesha Jabeen
- Department of Microbiology & Immunology, College of Medicine and Health Sciences, United Arab Emirates University, P.O. Box 17666, Al Ain, United Arab Emirates.
| | - Rawan M Kalloush
- Department of Microbiology & Immunology, College of Medicine and Health Sciences, United Arab Emirates University, P.O. Box 17666, Al Ain, United Arab Emirates.
| | - Delphine Richer
- Architecture et Réactivité de l'ARN, CNRS, IBMC, Université de Strasbourg, 15 rue René Descartes, 67084, Strasbourg cedex, France.
| | - Farah Mustafa
- Department of Biochemistry, College of Medicine and Health Sciences, United Arab Emirates University, Al Ain, United Arab Emirates.
| | - Roland Marquet
- Architecture et Réactivité de l'ARN, CNRS, IBMC, Université de Strasbourg, 15 rue René Descartes, 67084, Strasbourg cedex, France.
| | - Tahir A Rizvi
- Department of Microbiology & Immunology, College of Medicine and Health Sciences, United Arab Emirates University, P.O. Box 17666, Al Ain, United Arab Emirates.
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Al Shamsi IR, Al Dhaheri NS, Phillip PS, Mustafa F, Rizvi TA. Reciprocal cross-packaging of primate lentiviral (HIV-1 and SIV) RNAs by heterologous non-lentiviral MPMV proteins. Virus Res 2010; 155:352-7. [PMID: 20875467 DOI: 10.1016/j.virusres.2010.09.018] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2010] [Revised: 09/18/2010] [Accepted: 09/19/2010] [Indexed: 11/18/2022]
Abstract
Retroviral RNA packaging signal (ψ) allows the preferential packaging of genomic RNA into virus particles through its interaction with the nucleocapsid protein. The specificity of this interaction came into question when it was shown that primate retroviruses, such as HIV-1, could cross-package RNA from its simian cousin, SIV, and vice versa and that feline retrovirus, FIV could cross-package RNA from a distantly related primate retrovirus, MPMV. To study the generality of this phenomenon further, we determined whether there is a greater packaging restriction between the lentiviral class of retroviruses (HIV-1 and SIV) and a non-lentivirus, MPMV. Our results revealed that primate lentiviral RNAs can be cross-packaged by primate non-lentiviral particles reciprocally, but the cross-packaged RNAs could not be propagated by the heterologous particles. Packaging of RNA in the context of both retroviral vectors as well as non-retroviral RNA containing SIV, HIV, and MPMV packaging determinants by each others proteins further confirmed the specificity of cross-packaging conferred by the packaging sequences. These results reveal the promiscuous nature of retroviral packaging determinants and raise caution against their wide spread presence on retroviral vectors to be used for human gene therapy.
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Affiliation(s)
- Iman Rashed Al Shamsi
- Department of Microbiology & Immunology, Faculty of Medicine and Health Sciences, United Arab Emirates University, PO Box 17666, Al Ain, United Arab Emirates
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Al Dhaheri NS, Phillip PS, Ghazawi A, Ali J, Beebi E, Jaballah SA, Rizvi TA. Cross-packaging of genetically distinct mouse and primate retroviral RNAs. Retrovirology 2009; 6:66. [PMID: 19602292 PMCID: PMC2723071 DOI: 10.1186/1742-4690-6-66] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2009] [Accepted: 07/14/2009] [Indexed: 12/21/2022] Open
Abstract
Background The mouse mammary tumor virus (MMTV) is unique from other retroviruses in having multiple viral promoters, which can be regulated by hormones in a tissue specific manner. This unique property has lead to increased interest in studying MMTV replication with the hope of developing MMTV based vectors for human gene therapy. However, it has recently been reported that related as well as unrelated retroviruses can cross-package each other's genome raising safety concerns towards the use of candidate retroviral vectors for human gene therapy. Therefore, using a trans complementation assay, we looked at the ability of MMTV RNA to be cross-packaged and propagated by an unrelated primate Mason-Pfizer monkey virus (MPMV) that has intracellular assembly process similar to that of MMTV. Results Our results revealed that MMTV and MPMV RNAs could be cross-packaged by the heterologous virus particles reciprocally suggesting that pseudotyping between two genetically distinct retroviruses can take place at the RNA level. However, the cross-packaged RNAs could not be propagated further indicating a block at post-packaging events in the retroviral life cycle. To further confirm that the specificity of cross-packaging was conferred by the packaging sequences (ψ), we cloned the packaging sequences of these viruses on expression plasmids that generated non-viral RNAs. Test of these non-viral RNAs confirmed that the reciprocal cross-packaging was primarily due to the recognition of ψ by the heterologous virus proteins. Conclusion The results presented in this study strongly argue that MPMV and MMTV are promiscuous in their ability to cross-package each other's genome suggesting potential RNA-protein interactions among divergent retroviral RNAs proposing that these interactions are more complicated than originally thought. Furthermore, these observations raise the possibility that MMTV and MPMV genomes could also co-package providing substrates for exchanging genetic information.
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Affiliation(s)
- Noura Salem Al Dhaheri
- Department of Microbiology & Immunology, Faculty of Medicine and Health Sciences (FMHS), United Arab Emirates University (UAEU), Al Ain, UAE.
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Cheng X, Cheng X, Mukhtar M, Acheampong EA, Srinivasan A, Rafi M, Pomerantz RJ, Parveen Z. HIV-1 Vpr potently induces programmed cell death in the CNS in vivo. DNA Cell Biol 2007; 26:116-31. [PMID: 17328670 DOI: 10.1089/dna.2006.0541] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023] Open
Abstract
The human immunodeficiency virus type I (HIV-1) accessory protein Vpr has been associated with the induction of programmed cell death (apoptosis) and cell-cycle arrest. Studies have shown the apoptotic effect of Vpr on primary and established cell lines and on diverse tissues including the central nervous system (CNS) in vitro. However, the relevance of the effect of Vpr observed in vitro to HIV-1 neuropathogenesis in vivo, remains unknown. Due to the narrow host range of HIV-1 infection, no animal model is currently available. This has prompted us to consider a small animal model to evaluate the effects of Vpr on CNS in vivo through surrogate viruses expressing HIV-1Vpr. A single round of replication competent viral vectors, expressing Vpr, were used to investigate the apoptosis-inducing capabilities of HIV-1Vpr in vivo. Viral particles pseudotyped with VSV-G or N2c envelopes were generated from spleen necrosis virus (SNV) and HIV-1-based vectors to transduce CNS cells. The in vitro studies have demonstrated that Vpr generated by SNV vectors had less apoptotic effects on CNS cells compared with Vpr expressed by HIV-1 vectors. The in vivo study has suggested that viral particles, expressing Vpr generated by HIV-1-based vectors, when delivered through the ventricle, caused loss of neurons and dendritic processes in the cortical region. The apoptotic effect was extended beyond the cortical region and affected the hippocampus neurons, the lining of the choroids plexus, and the cerebellum. However, the effect of Vpr, when delivered through the cortex, showed neuronal damage only around the site of injection. Interestingly, the number of apoptotic neurons were significantly higher with HIV-1 vectors expressing Vpr than by the SNV vectors. This may be due to the differences in the proteins expressed by these viral vectors. These results suggest that Vpr induces apoptosis in CNS cells in vitro and in vivo. To our knowledge, this is the first study to investigate the apoptosis-inducing capabilities of HIV-1Vpr in vivo in neonatal mice. We propose that this, in expensive animal model, may be of value to design-targeted neuroprotective therapeutics.
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Affiliation(s)
- Xiaodong Cheng
- The Dorrance H. Hamilton Laboratories, Division of Infectious Diseases and Environmental Medicine, Department of Medicine, Jefferson Medical College, Thomas Jefferson University, Philadelphia, Pennsylvania, USA
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