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Hu M, Zheng H, Wu J, Sun Y, Wang T, Chen S. DDX5: an expectable treater for viral infection- a literature review. ANNALS OF TRANSLATIONAL MEDICINE 2022; 10:712. [PMID: 35845539 PMCID: PMC9279824 DOI: 10.21037/atm-22-2375] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Subscribe] [Scholar Register] [Received: 03/04/2022] [Accepted: 06/21/2022] [Indexed: 11/06/2022]
Abstract
Background and Objective DEAD-box protein (DDX)5 plays important roles in multiple aspects of cellular processes that require modulating RNA structure. Alongside the canonical role of DDX5 in RNA metabolism, many reports have shown that DDX5 influences viral infection by directly interacting with viral proteins. However, the functional role of DDX5 in virus-associated cancers, as well as the identity of DDX5 in virus infection-associated signaling pathways, has remained largely unexplained. Here, we further explore the precise functions of DDX5 and its potential targets for antiviral treatment. Methods We searched the PubMed and PMC databases to identify studies on role of DDXs, especially DDX5, during various viral infection published up to May 2022. Key Content and Findings DDX5 functions as both a viral infection helper and inhibitor, which depends on virus type. DDXs proteins have been identified to play roles on multiple aspects covering RNA metabolism and function. Conclusions DDX5 influences viral pathogenesis by participating in viral replication and multiple viral infection-related signaling pathways, it also plays a double-edge sword role under different viral infection conditions. Deep investigation into the mechanism of DDX5 modulating immune response in host cells revealed that it holds highly potential usage for future antiviral therapy. We reviewed current studies to provide a comprehensive update of the role of DDX5 in viral infection.
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Affiliation(s)
- Minghui Hu
- Clinical Lab, The Affiliated Hospital of Qingdao University, Qingdao China
| | - Hongying Zheng
- Clinical Lab, The Affiliated Hospital of Qingdao University, Qingdao China
| | - Jingqi Wu
- Microbiology Department, Harbin Medical University, Harbin, China
| | - Yue Sun
- School of Public Health, Harbin Medical University, Harbin, China
| | - Tianying Wang
- Clinical Research Center, Qingdao Municipal Hospital, Qingdao, China
| | - Shuang Chen
- Clinical Lab, Qingdao Municipal Hospital, Qingdao, China
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2
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Herrera-Carrillo E, Liu YP, Berkhout B. Improving miRNA Delivery by Optimizing miRNA Expression Cassettes in Diverse Virus Vectors. Hum Gene Ther Methods 2018; 28:177-190. [PMID: 28712309 DOI: 10.1089/hgtb.2017.036] [Citation(s) in RCA: 47] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022] Open
Abstract
The RNA interference pathway is an evolutionary conserved post-transcriptional gene regulation mechanism that is exclusively triggered by double-stranded RNA inducers. RNAi-based methods and technologies have facilitated the discovery of many basic science findings and spurred the development of novel RNA therapeutics. Transient induction of RNAi via transfection of synthetic small interfering RNAs can trigger the selective knockdown of a target mRNA. For durable silencing of gene expression, either artificial short hairpin RNA or microRNA encoding transgene constructs were developed. These miRNAs are based on the molecules that induce the natural RNAi pathway in mammals and humans: the endogenously expressed miRNAs. Significant efforts focused on the construction and delivery of miRNA cassettes in order to solve basic biology questions or to design new therapy strategies. Several viral vectors have been developed, which are particularly useful for the delivery of miRNA expression cassettes to specific target cells. Each vector system has its own unique set of distinct properties. Thus, depending on the specific application, a particular vector may be most suitable. This field was previously reviewed for different viral vector systems, and now the recent progress in the field of miRNA-based gene-silencing approaches using lentiviral vectors is reported. The focus is on the unique properties and respective limitations of the available vector systems for miRNA delivery.
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Affiliation(s)
- Elena Herrera-Carrillo
- Laboratory of Experimental Virology, Department of Medical Microbiology, Academic Medical Center, University of Amsterdam , Amsterdam, The Netherlands
| | - Ying Poi Liu
- Laboratory of Experimental Virology, Department of Medical Microbiology, Academic Medical Center, University of Amsterdam , Amsterdam, The Netherlands
| | - Ben Berkhout
- Laboratory of Experimental Virology, Department of Medical Microbiology, Academic Medical Center, University of Amsterdam , Amsterdam, The Netherlands
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Choy W, Lagman C, Lee SJ, Bui TT, Safaee M, Yang I. Impact of Human Immunodeficiency Virus in the Pathogenesis and Outcome of Patients with Glioblastoma Multiforme. Brain Tumor Res Treat 2016; 4:77-86. [PMID: 27867916 PMCID: PMC5114196 DOI: 10.14791/btrt.2016.4.2.77] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2016] [Revised: 07/10/2016] [Accepted: 07/18/2016] [Indexed: 12/25/2022] Open
Abstract
Background Improvement in antiviral therapies have been accompanied by an increased frequency of non-Acquired Immune Deficiency Syndrome (AIDS) defining malignancies, such as glioblastoma multiforme. Here, we investigated all reported cases of human immunodeficiency virus (HIV)-positive patients with glioblastoma and evaluated their clinical outcomes. A comprehensive review of the molecular pathogenetic mechanisms underlying glioblastoma development in the setting of HIV/AIDS is provided. Methods We performed a PubMed search using keywords “HIV glioma” AND “glioblastoma,” and “AIDS glioma” AND “glioblastoma.” Case reports and series describing HIV-positive patients with glioblastoma (histologically-proven World Health Organization grade IV astrocytoma) and reporting on HAART treatment status, clinical follow-up, and overall survival (OS), were included for the purposes of quantitative synthesis. Patients without clinical follow-up data or OS were excluded. Remaining articles were assessed for data extraction eligibility. Results A total of 17 patients met our inclusion criteria. Of these patients, 14 (82.4%) were male and 3 (17.6%) were female, with a mean age of 39.5±9.2 years (range 19–60 years). Average CD4 count at diagnosis of glioblastoma was 358.9±193.4 cells/mm3. Tumor progression rather than AIDS-associated complications dictated patient survival. There was a trend towards increased median survival with HAART treatment (12.0 vs 7.5 months, p=0.10) Conclusion Our data suggests that HAART is associated with improved survival in patients with HIV-associated glioblastoma, although the precise mechanisms underlying this improvement remain unclear.
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Affiliation(s)
- Winward Choy
- Department of Neurosurgery, University of California, Los Angeles, Los Angeles, CA, USA
| | - Carlito Lagman
- Department of Neurosurgery, University of California, Los Angeles, Los Angeles, CA, USA
| | - Seung J Lee
- Department of Neurosurgery, University of California, Los Angeles, Los Angeles, CA, USA
| | - Timothy T Bui
- Department of Neurosurgery, University of California, Los Angeles, Los Angeles, CA, USA
| | - Michael Safaee
- Department of Neurosurgery, University of California, Los Angeles, Los Angeles, CA, USA
| | - Isaac Yang
- Department of Neurosurgery, University of California, Los Angeles, Los Angeles, CA, USA.; Jonsson Comprehensive Cancer Center, University of California, Los Angeles, Los Angeles, CA, USA
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Ajamian L, Abel K, Rao S, Vyboh K, García-de-Gracia F, Soto-Rifo R, Kulozik AE, Gehring NH, Mouland AJ. HIV-1 Recruits UPF1 but Excludes UPF2 to Promote Nucleocytoplasmic Export of the Genomic RNA. Biomolecules 2015; 5:2808-39. [PMID: 26492277 PMCID: PMC4693258 DOI: 10.3390/biom5042808] [Citation(s) in RCA: 44] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2015] [Revised: 09/09/2015] [Accepted: 09/16/2015] [Indexed: 12/11/2022] Open
Abstract
Unspliced, genomic HIV-1 RNA (vRNA) is a component of several ribonucleoprotein complexes (RNP) during the viral replication cycle. In earlier work, we demonstrated that the host upframeshift protein 1 (UPF1), a key factor in nonsense-mediated mRNA decay (NMD), colocalized and associated to the viral structural protein Gag during viral egress. In this work, we demonstrate a new function for UPF1 in the regulation of vRNA nuclear export. OPEN ACCESS Biomolecules 2015, 5 2809 We establish that the nucleocytoplasmic shuttling of UPF1 is required for this function and demonstrate that UPF1 exists in two essential viral RNPs during the late phase of HIV-1 replication: the first, in a nuclear export RNP that contains Rev, CRM1, DDX3 and the nucleoporin p62, and the second, which excludes these nuclear export markers but contains Gag in the cytoplasm. Interestingly, we observed that both UPF2 and the long isoform of UPF3a, UPF3aL, but not the shorter isoforms UPF3aS and UPF3b, are excluded from the UPF1-Rev-CRM1-DDX3 complex as they are negative regulators of vRNA nuclear export. In silico protein-protein docking analyses suggest that Rev binds UPF1 in a region that overlaps the UPF2 binding site, thus explaining the exclusion of this negative regulatory factor by HIV-1 that is necessary for vRNA trafficking. This work uncovers a novel and unique regulatory circuit involving several UPF proteins that ultimately regulate vRNA nuclear export and trafficking.
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Affiliation(s)
- Lara Ajamian
- HIV-1 RNA Trafficking Laboratory, Lady Davis Institute for Medical Research-Sir Mortimer B. Davis Jewish General Hospital, Montréal QC H3T 1E2, Canada.
- Department of Medicine, Division of Experimental Medicine, McGill University, Montréal QC H3A 2B4, Canada.
| | - Karen Abel
- HIV-1 RNA Trafficking Laboratory, Lady Davis Institute for Medical Research-Sir Mortimer B. Davis Jewish General Hospital, Montréal QC H3T 1E2, Canada.
- Department of Microbiology and Immunology, McGill University, Montréal QC H3T 1E2, Canada.
| | - Shringar Rao
- HIV-1 RNA Trafficking Laboratory, Lady Davis Institute for Medical Research-Sir Mortimer B. Davis Jewish General Hospital, Montréal QC H3T 1E2, Canada.
- Department of Microbiology and Immunology, McGill University, Montréal QC H3T 1E2, Canada.
| | - Kishanda Vyboh
- HIV-1 RNA Trafficking Laboratory, Lady Davis Institute for Medical Research-Sir Mortimer B. Davis Jewish General Hospital, Montréal QC H3T 1E2, Canada.
- Department of Microbiology and Immunology, McGill University, Montréal QC H3T 1E2, Canada.
| | - Francisco García-de-Gracia
- Laboratory of Molecular and Cellular Virology, Virology Program, Biomedical Sciences Institute, Faculty of Medicine, Universidad de Chile, Independencia 8389100, Santiago, Chile.
| | - Ricardo Soto-Rifo
- Laboratory of Molecular and Cellular Virology, Virology Program, Biomedical Sciences Institute, Faculty of Medicine, Universidad de Chile, Independencia 8389100, Santiago, Chile.
| | - Andreas E Kulozik
- Department of Pediatric Oncology, Hematology and Immunology, Heidelberg 69120, Germany.
- European Molecular Biology Laboratory, Partnership Unit, University of Heidelberg Molecular Medicine, Heidelberg 69117, Germany.
| | - Niels H Gehring
- Institute for Genetics, University of Cologne, Cologne 50674, Germany.
| | - Andrew J Mouland
- HIV-1 RNA Trafficking Laboratory, Lady Davis Institute for Medical Research-Sir Mortimer B. Davis Jewish General Hospital, Montréal QC H3T 1E2, Canada.
- Department of Medicine, Division of Experimental Medicine, McGill University, Montréal QC H3A 2B4, Canada.
- Department of Microbiology and Immunology, McGill University, Montréal QC H3T 1E2, Canada.
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Taniguchi I, Mabuchi N, Ohno M. HIV-1 Rev protein specifies the viral RNA export pathway by suppressing TAP/NXF1 recruitment. Nucleic Acids Res 2014; 42:6645-58. [PMID: 24753416 PMCID: PMC4041468 DOI: 10.1093/nar/gku304] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/20/2013] [Revised: 03/31/2014] [Accepted: 03/31/2014] [Indexed: 01/11/2023] Open
Abstract
Nuclear RNA export pathways in eukaryotes are often linked to the fate of a given RNA. Therefore, the choice of export pathway should be well-controlled to avoid an unfavorable effect on gene expression. Although some RNAs could be exported by more than one pathway, little is known about how the choice is regulated. This issue is highlighted when the human immunodeficiency virus type 1 (HIV-1) Rev protein induces the export of singly spliced and unspliced HIV-1 transcripts. How these RNAs are exported is not well understood because such transcripts should have the possibility of utilizing CRM1-dependent export via Rev or cellular TAP/NXF1-dependent export via the transcription/export (TREX) complex, or both. Here we found that Rev suppressed TAP/NXF1-dependent export of model RNA substrates that recapitulated viral transcripts. In this effect, Rev interacted with the cap-binding complex and inhibited the recruitment of the TREX complex. Thus, Rev controls the identity of the factor occupying the cap-proximal region that determines the RNA export pathway. This ribonucleoprotein remodeling activity of Rev may favor viral gene expression.
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Affiliation(s)
- Ichiro Taniguchi
- Institute for Virus Research, Kyoto University, Kyoto 606-8507, Japan
| | - Naoto Mabuchi
- Institute for Virus Research, Kyoto University, Kyoto 606-8507, Japan
| | - Mutsuhito Ohno
- Institute for Virus Research, Kyoto University, Kyoto 606-8507, Japan
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Abstract
Numerous viral vectors have been developed for the delivery of transgenes to specific target cells. For persistent transgene expression, vectors based on retroviruses are attractive delivery vehicles because of their ability to stably integrate their DNA into the host cell genome. Initially, vectors based on simple retroviruses were the vector of choice for such applications. However, these vectors can only transduce actively dividing cells. Therefore, much interest has turned to retroviral vectors based on the lentivirus genus because of their ability to transduce both dividing and non-dividing cells. The best characterized lentiviral vectors are derived from the human immunodeficiency virus type 1 (HIV-1). This chapter describes the basic features of the HIV-1 replication cycle and the many improvements reported for the lentiviral vector systems to increase the safety and efficiency. We also provide practical information on the production of HIV-1 derived lentiviral vectors, the cell transduction protocol and a method to determine the transduction titers of a lentiviral vector.
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Affiliation(s)
- Ying Poi Liu
- Laboratory of Experimental Virology, Department of Medical Microbiology, Center for Infection and Immunity Amsterdam (CINIMA), Academic Medical Center, University of Amsterdam, Amsterdam, The Netherlands
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Gordon H, Ajamian L, Valiente-Echeverrìa F, Lévesque K, Rigby WF, Mouland AJ. Depletion of hnRNP A2/B1 overrides the nuclear retention of the HIV-1 genomic RNA. RNA Biol 2013; 10:1714-25. [PMID: 24157614 DOI: 10.4161/rna.26542] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
Abstract
hnRNP A2 is a cellular protein that is important for nucleocytoplasmic and cytosolic trafficking of the HIV-1 genomic RNA. Both hnRNP A2's interaction with HIV-1 RNA and its expression levels influence the activities of Rev in mediating nucleocytoplasmic export of the HIV-1 genomic RNA. While the lack of Rev expression during HIV-1 gene expression results in nuclear retention of HIV-1 genomic RNA, we show here by fluorescence in situ hybridization and fractionation studies that the genomic RNA translocates to the cytoplasm when hnRNP A2/B1 are depleted from cells. Polyribosome analyses revealed that the genomic RNA was shunted into a cytoplasmic, dense polyribosomal fraction. This fraction contained several RNA-binding proteins involved in viral gene expression and RNA trafficking but did not contain the translation initiation factor, eIF4G1. Amino acid incorporation into nascent polypeptides in this fraction was also greatly reduced, demonstrating that this fraction contains mRNAs that are poorly translated. These results demonstrate that hnRNP A2/B1 expression plays roles in the nuclear retention of the HIV-1 genomic RNA in the absence of Rev and in the release of the genomic RNA from translationally inactive, cytoplasmic RNP complexes.
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Affiliation(s)
- Heather Gordon
- HIV-1 RNA Trafficking Laboratory; Lady Davis Institute at the Jewish General Hospital; Montréal, Québec, Canada; Department of Microbiology & Immunology; McGill University; Montréal, Québec, Canada
| | - Lara Ajamian
- HIV-1 RNA Trafficking Laboratory; Lady Davis Institute at the Jewish General Hospital; Montréal, Québec, Canada; Department of Medicine; Division of Experimental Medicine; McGill University; Montréal, Québec, Canada
| | - Fernando Valiente-Echeverrìa
- HIV-1 RNA Trafficking Laboratory; Lady Davis Institute at the Jewish General Hospital; Montréal, Québec, Canada; Department of Medicine; Division of Experimental Medicine; McGill University; Montréal, Québec, Canada
| | - Kathy Lévesque
- HIV-1 RNA Trafficking Laboratory; Lady Davis Institute at the Jewish General Hospital; Montréal, Québec, Canada; Department of Medicine; Division of Experimental Medicine; McGill University; Montréal, Québec, Canada
| | - William F Rigby
- Dartmouth Medical School; Department of Medicine; Lebanon, NH, USA
| | - Andrew J Mouland
- HIV-1 RNA Trafficking Laboratory; Lady Davis Institute at the Jewish General Hospital; Montréal, Québec, Canada; Department of Microbiology & Immunology; McGill University; Montréal, Québec, Canada; Department of Medicine; Division of Experimental Medicine; McGill University; Montréal, Québec, Canada
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8
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Zhou X, Luo J, Mills L, Wu S, Pan T, Geng G, Zhang J, Luo H, Liu C, Zhang H. DDX5 facilitates HIV-1 replication as a cellular co-factor of Rev. PLoS One 2013; 8:e65040. [PMID: 23741449 PMCID: PMC3669200 DOI: 10.1371/journal.pone.0065040] [Citation(s) in RCA: 41] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/02/2013] [Accepted: 04/21/2013] [Indexed: 12/21/2022] Open
Abstract
HIV-1 Rev plays an important role in the late phase of HIV-1 replication, which facilitates export of unspliced viral mRNAs from the nucleus to cytoplasm in infected cells. Recent studies have shown that DDX1 and DDX3 are co-factors of Rev for the export of HIV-1 transcripts. In this report, we have demonstrated that DDX5 (p68), which is a multifunctional DEAD-box RNA helicase, functions as a new cellular co-factor of HIV-1 Rev. We found that DDX5 affects Rev function through the Rev-RRE axis and subsequently enhances HIV-1 replication. Confocal microscopy and co-immunoprecipitation analysis indicated that DDX5 binds to Rev and this interaction is largely dependent on RNA. If the DEAD-box motif of DDX5 is mutated, DDX5 loses almost all of its ability to bind to Rev, indicating that the DEAD-box motif of DDX5 is required for the interaction between DDX5 and Rev. Our data indicate that interference of DDX5-Rev interaction could reduce HIV-1 replication and potentially provide a new molecular target for anti-HIV-1 therapeutics.
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Affiliation(s)
- Xiuxia Zhou
- Institute of Human Virology, Zhongshan School of Medicine, Sun Yat-sen University, Guangzhou, China
- Key Laboratory of Tropical Disease Control of Ministry of Education, Zhongshan School of Medicine, Sun Yat-sen University, Guangzhou, China
- Cyrus Tang Hematology Center, Jiangsu Institute of Hematology, First Affiliated Hospital, Soochow University, Suzhou, China
| | - Juan Luo
- Institute of Human Virology, Zhongshan School of Medicine, Sun Yat-sen University, Guangzhou, China
- Key Laboratory of Tropical Disease Control of Ministry of Education, Zhongshan School of Medicine, Sun Yat-sen University, Guangzhou, China
| | - Lisa Mills
- Center for Human Virology, Division of Infectious Diseases, Department of Medicine, Thomas Jefferson University, Philadelphia, Pennsylvania, United States of America
| | - Shuangxin Wu
- Institute of Human Virology, Zhongshan School of Medicine, Sun Yat-sen University, Guangzhou, China
- Key Laboratory of Tropical Disease Control of Ministry of Education, Zhongshan School of Medicine, Sun Yat-sen University, Guangzhou, China
| | - Ting Pan
- Institute of Human Virology, Zhongshan School of Medicine, Sun Yat-sen University, Guangzhou, China
- Key Laboratory of Tropical Disease Control of Ministry of Education, Zhongshan School of Medicine, Sun Yat-sen University, Guangzhou, China
| | - Guannan Geng
- Institute of Human Virology, Zhongshan School of Medicine, Sun Yat-sen University, Guangzhou, China
- Key Laboratory of Tropical Disease Control of Ministry of Education, Zhongshan School of Medicine, Sun Yat-sen University, Guangzhou, China
| | - Jim Zhang
- Center for Human Virology, Division of Infectious Diseases, Department of Medicine, Thomas Jefferson University, Philadelphia, Pennsylvania, United States of America
| | - Haihua Luo
- Institute of Human Virology, Zhongshan School of Medicine, Sun Yat-sen University, Guangzhou, China
- Key Laboratory of Tropical Disease Control of Ministry of Education, Zhongshan School of Medicine, Sun Yat-sen University, Guangzhou, China
| | - Chao Liu
- Institute of Human Virology, Zhongshan School of Medicine, Sun Yat-sen University, Guangzhou, China
- Key Laboratory of Tropical Disease Control of Ministry of Education, Zhongshan School of Medicine, Sun Yat-sen University, Guangzhou, China
- * E-mail: (HZ); (CL)
| | - Hui Zhang
- Institute of Human Virology, Zhongshan School of Medicine, Sun Yat-sen University, Guangzhou, China
- Key Laboratory of Tropical Disease Control of Ministry of Education, Zhongshan School of Medicine, Sun Yat-sen University, Guangzhou, China
- Center for Human Virology, Division of Infectious Diseases, Department of Medicine, Thomas Jefferson University, Philadelphia, Pennsylvania, United States of America
- * E-mail: (HZ); (CL)
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Vincendeau M, Nagel D, Brenke JK, Brack-Werner R, Hadian K. Heterogenous nuclear ribonucleoprotein Q increases protein expression from HIV-1 Rev-dependent transcripts. Virol J 2013; 10:151. [PMID: 23679954 PMCID: PMC3673855 DOI: 10.1186/1743-422x-10-151] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/05/2012] [Accepted: 03/19/2013] [Indexed: 02/05/2023] Open
Abstract
Background Heterogenous nuclear ribonucleoproteins (hnRNPs) control many processes of the gene expression machinery including mRNA transcription, splicing, export, stability and translation. Recent data show interaction of the HIV-1 Rev regulatory protein with a subset of hnRNP proteins, that includes hnRNP Q, suggesting that hnRNPs can contribute to regulation of HIV-1 gene expression by Rev. Findings In this work we address the effect of hnRNP Q on Rev-dependent gene expression. We show that hnRNP Q overexpression increased levels of proteins produced from a Rev-dependent reporter gene in the presence of Rev. Increased protein levels did not correlate with changes in either the levels or the nucleocytoplasmic distribution of Rev-dependent reporter mRNAs. Similar observations were made in persistently HIV-1 infected HeLa cells. In these cells, hnRNP Q overexpression increased levels of the HIV-1 Gag-p24 protein, while levels of viral Rev-dependent mRNAs were not affected. Conclusion Our data indicate that hnRNP Q can stimulate the protein production of Rev-dependent mRNAs without changing mRNA levels and mRNA export, respectively. This suggests that hnRNP Q can boost HIV gene expression at the level of protein production.
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Affiliation(s)
- Michelle Vincendeau
- Institute of Virology, Helmholtz Zentrum München, Research Center for Environmental Health, Ingolstaedter Landstraße 1, 85764 Neuherberg, Germany
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10
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Hoffmann D, Schwarck D, Banning C, Brenner M, Mariyanna L, Krepstakies M, Schindler M, Millar DP, Hauber J. Formation of trans-activation competent HIV-1 Rev:RRE complexes requires the recruitment of multiple protein activation domains. PLoS One 2012; 7:e38305. [PMID: 22675540 PMCID: PMC3366918 DOI: 10.1371/journal.pone.0038305] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2012] [Accepted: 05/07/2012] [Indexed: 12/13/2022] Open
Abstract
The HIV-1 Rev trans-activator is a nucleocytoplasmic shuttle protein that is essential for virus replication. Rev directly binds to unspliced and incompletely spliced viral RNA via the cis-acting Rev Response Element (RRE) sequence. Subsequently, Rev oligomerizes cooperatively and interacts with the cellular nuclear export receptor CRM1. In addition to mediating nuclear RNA export, Rev also affects the stability, translation and packaging of Rev-bound viral transcripts. Although it is established that Rev function requires the multimeric assembly of Rev molecules on the RRE, relatively little is known about how many Rev monomers are sufficient to form a trans-activation competent Rev:RRE complex, or which specific activity of Rev is affected by its oligomerization. We here analyzed by functional studies how homooligomer formation of Rev affects the trans-activation capacity of this essential HIV-1 regulatory protein. In a gain-of-function approach, we fused various heterologous dimerization domains to an otherwise oligomerization-defective Rev mutant and were able to demonstrate that oligomerization of Rev is not required per se for the nuclear export of this viral trans-activator. In contrast, however, the formation of Rev oligomers on the RRE is a precondition to trans-activation by directly affecting the nuclear export of Rev-regulated mRNA. Moreover, experimental evidence is provided showing that at least two protein activation domains are required for the formation of trans-activation competent Rev:RRE complexes. The presented data further refine the model of Rev trans-activation by directly demonstrating that Rev oligomerization on the RRE, thereby recruiting at least two protein activation domains, is required for nuclear export of unspliced and incompletely spliced viral RNA.
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Affiliation(s)
- Dirk Hoffmann
- Heinrich Pette Institute – Leibniz Institute for Experimental Virology, Hamburg, Germany
| | - Doreen Schwarck
- Heinrich Pette Institute – Leibniz Institute for Experimental Virology, Hamburg, Germany
| | - Carina Banning
- Heinrich Pette Institute – Leibniz Institute for Experimental Virology, Hamburg, Germany
| | - Matthias Brenner
- Institute for Clinical and Molecular Virology, University of Erlangen-Nuremberg, Erlangen, Germany
| | - Lakshmikanth Mariyanna
- Heinrich Pette Institute – Leibniz Institute for Experimental Virology, Hamburg, Germany
| | - Marcel Krepstakies
- Heinrich Pette Institute – Leibniz Institute for Experimental Virology, Hamburg, Germany
| | - Michael Schindler
- Heinrich Pette Institute – Leibniz Institute for Experimental Virology, Hamburg, Germany
| | - David P. Millar
- Department of Molecular Biology, The Scripps Research Institute, La Jolla, California, United States of America
| | - Joachim Hauber
- Heinrich Pette Institute – Leibniz Institute for Experimental Virology, Hamburg, Germany
- * E-mail:
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11
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Liu YP, Berkhout B. miRNA cassettes in viral vectors: problems and solutions. BIOCHIMICA ET BIOPHYSICA ACTA-GENE REGULATORY MECHANISMS 2011; 1809:732-45. [PMID: 21679781 DOI: 10.1016/j.bbagrm.2011.05.014] [Citation(s) in RCA: 64] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/01/2011] [Revised: 05/25/2011] [Accepted: 05/27/2011] [Indexed: 02/05/2023]
Abstract
The discovery of RNA interference (RNAi), an evolutionary conserved gene silencing mechanism that is triggered by double stranded RNA, has led to tremendous efforts to use this technology for basic research and new RNA therapeutics. RNAi can be induced via transfection of synthetic small interfering RNAs (siRNAs), which results in a transient knockdown of the targeted mRNA. For stable gene silencing, short hairpin RNA (shRNA) or microRNA (miRNA) constructs have been developed. In mammals and humans, the natural RNAi pathway is triggered via endogenously expressed miRNAs. The use of modified miRNA expression cassettes to elucidate fundamental biological questions or to develop therapeutic strategies has received much attention. Viral vectors are particularly useful for the delivery of miRNA genes to specific target cells. To date, many viral vectors have been developed, each with distinct characteristics that make one vector more suitable for a certain purpose than others. This review covers the recent progress in miRNA-based gene-silencing approaches that use viral vectors, with a focus on their unique properties, respective limitations and possible solutions. Furthermore, we discuss a related topic that involves the insertion of miRNA-target sequences in viral vector systems to restrict their cellular range of gene expression. This article is part of a Special Issue entitled: MicroRNAs in viral gene regulation.
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Affiliation(s)
- Ying Poi Liu
- Department of Medical Microbiology, University of Amsterdam, Amsterdam, the Netherlands
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Tamura S, Murakami N. Exploration of Novel Medicinal Leads by Use of Natural Products Inhibiting Nuclear Export of Proteins as Scaffolds. J SYN ORG CHEM JPN 2011. [DOI: 10.5059/yukigoseikyokaishi.69.393] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
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Control of HIV replication in astrocytes by a family of highly conserved host proteins with a common Rev-interacting domain (Risp). AIDS 2010; 24:2433-42. [PMID: 20827171 DOI: 10.1097/qad.0b013e32833e8758] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
OBJECTIVE In human astrocytes, restriction of HIV replication involves inhibition of HIV Rev activity. We previously identified a Rev-interacting human protein fragment (16.4.1) that can reduce Rev activity. The 16.4.1 sequence is contained in a group of highly similar host cell proteins, which we call the Risp family. Here we investigate whether the Risp family is connected to HIV replication in astrocytes. METHODS Cell/tissue lysates were analyzed for Risp expression by western blot with various anti-Risp antibodies. The interaction of astrocytic Risp members with Rev was investigated by affinity chromatography. Astrocytes were transfected with expression plasmids containing cDNAs encoding full-length Risp or the isolated 16.4.1 region for Risp overexpression or with siRNAs designed for Risp knock-down. Rev activity was investigated with a Rev-reporter assay. RNA levels were quantified by real-time RT-PCR, HIV Gag levels by p24ELISA. RESULTS Expression of the Risp family was demonstrated in human brain tissues and astrocytes. Astrocytes were shown to produce Risp family members that interact with Rev. Production of HIV Gag proteins and Rev-dependent RNAs in persistently infected astrocytes increased upon Risp knock-down and decreased upon Risp overexpression. Risp knock-down increased Rev activity and raised proportions of Rev proteins in the nucleus of astrocytes. CONCLUSION Our results link the Risp family to restriction of HIV production and inhibition of Rev activity in astrocytes. We conclude that the Risp family represents a novel family of host factors that can control HIV replication and may be important for the containment of HIV infection in brain reservoirs.
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Strategies to inhibit viral protein nuclear import: HIV-1 as a target. BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR CELL RESEARCH 2010; 1813:1646-53. [PMID: 20719241 DOI: 10.1016/j.bbamcr.2010.07.010] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/22/2010] [Revised: 07/16/2010] [Accepted: 07/29/2010] [Indexed: 12/22/2022]
Abstract
Nuclear import is a critical step in the life cycle of HIV-1. During the early (preintegration) stages of infection, HIV-1 has to transport its preintegration complex into the nucleus for integration into the host cell chromatin, while at the later (postintegration) stages viral regulatory proteins Tat and Rev need to get into the nucleus to stimulate transcription and regulate splicing and nuclear export of subgenomic and genomic RNAs. Given such important role of nuclear import in HIV-1 life cycle, this step presents an attractive target for antiviral therapeutic intervention. In this review, we describe the current state of our understanding of the interactions regulating nuclear import of the HIV-1 preintegration complex and describe current approaches to inhibit it. This article is part of a Special Issue entitled: Regulation of Signaling and Cellular Fate through Modulation of Nuclear Protein Import.
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15
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Tamura S, Fujiwara K, Shimizu N, Todo S, Murakami N. Concise synthesis of 5,6-dihydrovaltrate leading to enhanced Rev-export inhibitory congener. Bioorg Med Chem 2010; 18:5975-80. [DOI: 10.1016/j.bmc.2010.06.079] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/03/2010] [Revised: 06/21/2010] [Accepted: 06/22/2010] [Indexed: 11/15/2022]
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16
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Levin A, Hayouka Z, Friedler A, Loyter A. Over-expression of the HIV-1 Rev promotes death of nondividing eukaryotic cells. Virus Genes 2010; 40:341-6. [PMID: 20151187 DOI: 10.1007/s11262-010-0458-7] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/22/2009] [Accepted: 01/30/2010] [Indexed: 10/19/2022]
Abstract
Expression of the human immunodeficiency virus type 1 (HIV-1) Rev protein is essential for completion of the viral life cycle. Rev mediates nuclear export of partially spliced and unspliced viral transcripts and therefore bears a nuclear localization signal (NLS) as well as a nuclear export signal (NES), which allow its nucleocytoplasmic shuttling. Attempts to express the wild-type Rev protein in eukaryotic human cultured cells have encountered difficulties and so far have failed. Here we show that accumulation of Rev, which occurs in nondividing Rev-expressing cells or when such cells reach confluency, results in death of these cells. Cell death was also promoted by addition of a cell permeable peptide bearing the Rev-NES sequence, but not by the Rev-NLS peptide. Our results probably indicate that binding of excess amounts of the Rev protein or the NES peptide to the exportin receptor CRM1 results in cells' death.
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Affiliation(s)
- Aviad Levin
- Department of Biological Chemistry, The Alexander Silberman Institute of Life Sciences, The Hebrew University of Jerusalem, Jerusalem, Israel
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17
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Prenylcoumarin with Rev-export inhibitory activity from Cnidii Monnieris Fructus. Bioorg Med Chem Lett 2010; 20:3717-20. [PMID: 20493693 DOI: 10.1016/j.bmcl.2010.04.081] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2010] [Revised: 04/15/2010] [Accepted: 04/19/2010] [Indexed: 11/20/2022]
Abstract
By use of the fission yeast expressing the model fusion protein comprised of GST, SV40 T antigen NLS, GFP, and Rev-NES in the bioassay, the prenylcoumarin osthol (1) was disclosed as the new Rev-export inhibitor from the MeOH extract of Cnidii Monnieris Fructus. Furthermore, 1 was also found to inhibit export the genuine Rev in HeLa cells by indirect fluorescent antibody technique. By the competitive experiment using the biotinylated probe 3, osthol (1) was revealed to inhibit nuclear export of Rev through a NES non-antagonistic mode. Structure-activity relationship analysis of several analogs of 1 clarified that both prenyl side chain and double bond adjacent to the lactone carbonyl residue play an important role in the Rev-export inhibitory potency of 1.
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18
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Tamura S, Kaneko M, Shiomi A, Yang GM, Yamaura T, Murakami N. Unprecedented NES non-antagonistic inhibitor for nuclear export of Rev from Sida cordifolia. Bioorg Med Chem Lett 2010; 20:1837-9. [DOI: 10.1016/j.bmcl.2010.01.165] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2009] [Revised: 01/26/2010] [Accepted: 01/30/2010] [Indexed: 11/26/2022]
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19
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Tamura S, Shiomi A, Kimura T, Murakami N. Halogenated analogs of 1'-acetoxychavicol acetate, Rev-export inhibitor from Alpinia galanga, designed from mechanism of action. Bioorg Med Chem Lett 2010; 20:2082-5. [PMID: 20219373 DOI: 10.1016/j.bmcl.2010.02.070] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2010] [Revised: 02/16/2010] [Accepted: 02/17/2010] [Indexed: 11/16/2022]
Abstract
In the course of search for the robust analogs of 1'-acetoxychavicol acetate (ACA, 1), the Rev-export inhibitor from the medicinal plant Alpinia galanga, we clarified formation of the quinone methide intermediate ii to be essential for exerting the inhibitory activity of 1. Based on this mechanism of action, the rational design from the MO calculation of the conclusive activation energy to ii resulted in the four halogenated analogs with more potent activity than ACA (1). In particular, the difluoroanalog 20d exhibited approximately four-fold potent activity as compared with 1.
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Affiliation(s)
- Satoru Tamura
- Graduate School of Pharmaceutical Sciences, Osaka University, 1-6 Yamada-oka, Suita, Osaka 565-0871, Japan
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20
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The bovine immunodeficiency virus rev protein: identification of a novel lentiviral bipartite nuclear localization signal harboring an atypical spacer sequence. J Virol 2009; 83:12842-53. [PMID: 19828621 DOI: 10.1128/jvi.01613-09] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The bovine immunodeficiency virus (BIV) Rev protein (186 amino acids [aa] in length) is involved in the nuclear exportation of partially spliced and unspliced viral RNAs. Previous studies have shown that BIV Rev localizes in the nucleus and nucleolus of infected cells. Here we report the characterization of the nuclear/nucleolar localization signals (NLS/NoLS) of this protein. Through transfection of a series of deletion mutants of BIV Rev fused to enhanced green fluorescent protein and fluorescence microscopy analyses, we were able to map the NLS region between aa 71 and 110 of the protein. Remarkably, by conducting alanine substitution of basic residues within the aa 71 to 110 sequence, we demonstrated that the BIV Rev NLS is bipartite, maps to aa 71 to 74 and 95 to 101, and is predominantly composed of arginine residues. This is the first report of a bipartite Rev (or Rev-like) NLS in a lentivirus/retrovirus. Moreover, this NLS is atypical, as the length of the sequence between the motifs composing the bipartite NLS, e.g., the spacer sequence, is 20 aa. Further mutagenesis experiments also identified the NoLS region of BIV Rev. It localizes mainly within the NLS spacer sequence. In addition, the BIV Rev NoLS sequence differs from the consensus sequence reported for other viral and cellular nucleolar proteins. In summary, we conclude that the nucleolar and nuclear localizations of BIV Rev are mediated via novel NLS and NoLS motifs.
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21
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Hadian K, Vincendeau M, Mäusbacher N, Nagel D, Hauck SM, Ueffing M, Loyter A, Werner T, Wolff H, Brack-Werner R. Identification of a heterogeneous nuclear ribonucleoprotein-recognition region in the HIV Rev protein. J Biol Chem 2009; 284:33384-91. [PMID: 19808671 DOI: 10.1074/jbc.m109.021659] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The Rev protein is a key regulator of human immunodeficiency virus type 1 (HIV-1) gene expression. Rev is primarily known as an adaptor protein for nuclear export of HIV RNAs. However, Rev also contributes to numerous other processes by less well known mechanisms. Understanding the functional nature of Rev requires extensive knowledge of its cellular interaction partners. Here we demonstrate that Rev interacts with members of a large family of multifunctional host cell factors called hnRNPs. Rev employs amino acids 9-14 for specific binding to the heterogeneous nuclear ribonucleoproteins (hnRNP) A1, Q, K, R, and U. In addition, Rev interacts with hnRNP E1 and E2 by a different mechanism. The set of hnRNPs recognized by the N terminus of Rev feature RGG boxes. Exemplary testing of hnRNP A1 revealed a critical role of arginine residues within the RGG box for interaction with Rev. Finally, we demonstrate that expression levels of hnRNP A1, Q, K, R, and U influence HIV-1 production by persistently infected astrocytes, linking these hnRNPs to HIV replication. The novel interaction of HIV-1 Rev with functionally diverse hnRNPs lends further support to the idea that Rev is a multifunctional protein and may be involved in coupling HIV replication to diverse cellular processes and promoting virus-host cell interactions.
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Affiliation(s)
- Kamyar Hadian
- Institute of Virology, Helmholtz Zentrum München, Research Center for Environmental Health, Ingolstaedter Landstrasse 1, D-85764 Neuherberg, Germany
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22
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Lehmann M, Milev MP, Abrahamyan L, Yao XJ, Pante N, Mouland AJ. Intracellular transport of human immunodeficiency virus type 1 genomic RNA and viral production are dependent on dynein motor function and late endosome positioning. J Biol Chem 2009; 284:14572-85. [PMID: 19286658 PMCID: PMC2682905 DOI: 10.1074/jbc.m808531200] [Citation(s) in RCA: 63] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/10/2008] [Revised: 03/03/2009] [Indexed: 11/06/2022] Open
Abstract
Our earlier work indicated that the human immunodeficiency virus type 1 (HIV-1) genomic RNA (vRNA) is trafficked to the microtubule-organizing center (MTOC) when heterogeneous nuclear ribonucleoprotein A2/B1 is depleted from cells. Also, Rab7-interacting lysosomal protein promoted dynein motor complex, late endosome and vRNA clustering at the MTOC suggesting that the dynein motor and late endosomes were involved in vRNA trafficking. To investigate the role of the dynein motor in vRNA trafficking, dynein motor function was disrupted by small interference RNA-mediated depletion of the dynein heavy chain or by p50/dynamitin overexpression. These treatments led to a marked relocalization of vRNA and viral structural protein Gag to the cell periphery with late endosomes and a severalfold increase in HIV-1 production. In contrast, rerouting vRNA to the MTOC reduced virus production. vRNA localization depended on Gag membrane association as shown using both myristoylation and Gag nucleocapsid domain proviral mutants. Furthermore, the cytoplasmic localization of vRNA and Gag was not attributable to intracellular or internalized endocytosed virus particles. Our results demonstrate that dynein motor function is important for regulating Gag and vRNA egress on endosomal membranes in the cytoplasm to directly impact on viral production.
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Affiliation(s)
- Martin Lehmann
- HIV-1 RNA Trafficking Laboratory, Lady Davis Institute for Medical Research, Quebec
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23
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Tamura S, Shiomi A, Kaneko M, Ye Y, Yoshida M, Yoshikawa M, Kimura T, Kobayashi M, Murakami N. New Rev-export inhibitor from Alpinia galanga and structure-activity relationship. Bioorg Med Chem Lett 2009; 19:2555-7. [PMID: 19342232 DOI: 10.1016/j.bmcl.2009.03.047] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2009] [Accepted: 03/07/2009] [Indexed: 11/28/2022]
Abstract
Bioassay-guided separation by use of the fission yeast expressing NES of Rev, an HIV-1 viral regulatory protein, disclosed 1'-acetoxychavicol acetate (ACA, 1) as a new inhibitor for nuclear export of Rev from the roots of Alpinia galanga. Both analysis for mechanism of action with biotinylated probe (2) and several synthesized analogs established crucial portions in 1 for Rev-export inhibitory activity.
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Affiliation(s)
- Satoru Tamura
- Graduate School of Pharmaceutical Sciences, Osaka University, 1-6 Yamada-oka, Suita, Osaka 565-0871, Japan
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24
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HIV-1 Vif protein mediates the degradation of APOBEC3G in fission yeast when over-expressed using codon optimization. Virol Sin 2008. [DOI: 10.1007/s12250-008-2957-4] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023] Open
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25
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Kaminski R, Darbinian N, Sawaya BE, Slonina D, Amini S, Johnson EM, Rappaport J, Khalili K, Darbinyan A. Puralpha as a cellular co-factor of Rev/RRE-mediated expression of HIV-1 intron-containing mRNA. J Cell Biochem 2008; 103:1231-45. [PMID: 17722108 PMCID: PMC2575347 DOI: 10.1002/jcb.21503] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Abstract
To ensure successful replication, HIV-1 has developed a Rev-mediated RNA transport system that promotes the export of unspliced genomic RNA from nuclei to cytoplasm. This process requires the Rev responsive element (RRE) that is positioned in the viral transcript encoding Env protein, as well as in unspliced and singly spliced viral transcripts. We identified Puralpha, a single-stranded nucleic acid binding protein as a cellular partner for Rev that augments the appearance of unspliced viral RNAs in the cytoplasm. A decrease in the level of Puralpha expression by siRNA diminishes the level of Rev-dependent expression of viral RNA. Through its nucleic acid binding domain, Puralpha exhibits the ability to interact with the multimerization and RBD domains of Rev. Similar to Rev, Puralpha associates with RRE and in the presence of Rev forms a complex with slower electrophoretic mobility than those from Rev:RRE and Puralpha:RRE. The interaction of Puralpha with RRE occurs in the cytoplasm where enhanced association of Rev with RRE is observed. Our data indicate that the partnership of Puralpha with Rev is beneficial for Rev-mediated expression of the HIV-1 genome.
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Affiliation(s)
- Rafal Kaminski
- Department of Neuroscience, Center for Neurovirology, Temple University School of Medicine, Philadelphia, Pennsylvania 19122, USA
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26
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Abstract
BACKGROUND HIV can reside in the brain for many years. While astrocytes are known to tolerate long-term HIV infection, the potential of other neural cell types to harbour HIV is unclear. OBJECTIVE To investigate whether HIV can persist in neural progenitor cell populations. DESIGN A multipotent human neural stem cell line (HNSC.100) was used to compare HIV infection in neural progenitor and astrocyte cell populations. METHODS Expression of cellular genes/proteins was analysed by real-time reverse transcriptase PCR, Western blot, immunocytochemistry and flow cytometry. Morphological properties of cells were measured by quantitative fluorescent image analysis. Virus release by cells exposed to HIV-1IIIB was monitored by enzyme-linked immunosorbent assay for Gag. Proviral copy numbers were determined by real-time PCR and early HIV transcripts by reverse transcriptase PCR. Rev activity was determined with a fluorescent-based reporter assay. RESULTS Progenitor populations differed from astrocyte populations by showing much lower glial fibrillary acidic protein (GFAP) production, higher cell-surface expression of the CXCR4 chemokine receptor, higher Rev activity and distinct cell morphologies. HIV-exposed progenitor cultures released moderate amounts of virus for over 2 months and continued to display cell-associated HIV markers (proviral DNA, early HIV transcripts) during the entire observation period (115 days). Differentiation of HIV-infected progenitor cells to astrocytes was associated with transient activation of virus production. Long-term HIV infection of progenitor populations led to upregulation of GFAP and changes in cell morphology. CONCLUSION These studies suggest that neural progenitor populations can contribute to the reservoir for HIV in the brain and undergo changes as a consequence of HIV persistence.
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27
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Abstract
The retroviral Gag polyprotein directs virus particle assembly, resulting in the release of virions from the plasma membranes of infected cells. The earliest steps in assembly, those immediately following Gag synthesis, are very poorly understood. For Rous sarcoma virus (RSV), Gag proteins are synthesized in the cytoplasm and then undergo transient nuclear trafficking before returning to the cytoplasm for transport to the plasma membrane. Thus, RSV provides a useful model to study the initial steps in assembly because the early and later stages are spatially separated by the nuclear envelope. We previously described mutants of RSV Gag that are defective in nuclear export, thereby isolating these "trapped" Gag proteins at an early assembly step. Using the nuclear export mutants, we asked whether Gag protein-protein interactions occur within the nucleus. Complementation experiments revealed that the wild-type Gag protein could partially rescue export-defective Gag mutants into virus-like particles (VLPs). Additionally, the export mutants had a trans-dominant negative effect on wild-type Gag, interfering with its release into VLPs. Confocal imaging of wild-type and mutant Gag proteins bearing different fluorescent tags suggested that complementation between Gag proteins occurred in the nucleus. Additional evidence for nuclear Gag-Gag interactions was obtained using fluorescence resonance energy transfer, and we found that the formation of intranuclear Gag complexes was dependent on the NC domain. Bimolecular fluorescence complementation allowed the direct visualization of intranuclear Gag-Gag dimers. Together, these experimental results strongly suggest that RSV Gag proteins are capable of interacting within the nucleus.
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28
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Churchill MJ, Chiavaroli L, Wesselingh SL, Gorry PR. Persistence of attenuated HIV-1 rev alleles in an epidemiologically linked cohort of long-term survivors infected with nef-deleted virus. Retrovirology 2007; 4:43. [PMID: 17601342 PMCID: PMC1933581 DOI: 10.1186/1742-4690-4-43] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2007] [Accepted: 07/01/2007] [Indexed: 11/10/2022] Open
Abstract
Background The Sydney blood bank cohort (SBBC) of long-term survivors consists of multiple individuals infected with nef-deleted, attenuated strains of human immunodeficiency virus type 1 (HIV-1). Although the cohort members have experienced differing clinical courses and now comprise slow progressors (SP) as well as long-term nonprogressors (LTNP), longitudinal analysis of nef/long-terminal repeat (LTR) sequences demonstrated convergent nef/LTR sequence evolution in SBBC SP and LTNP. Thus, the in vivo pathogenicity of attenuated HIV-1 strains harboured by SBBC members is dictated by factors other than nef/LTR. Therefore, to determine whether defects in other viral genes contribute to attenuation of these HIV-1 strains, we characterized dominant HIV-1 rev alleles that persisted in 4 SBBC subjects; C18, C64, C98 and D36. Results The ability of Rev derived from D36 and C64 to bind the Rev responsive element (RRE) in RNA binding assays was reduced by approximately 90% compared to Rev derived from HIV-1NL4-3, C18 or C98. D36 Rev also had a 50–60% reduction in ability to express Rev-dependent reporter constructs in mammalian cells. In contrast, C64 Rev had only marginally decreased Rev function despite attenuated RRE binding. In D36 and C64, attenuated RRE binding was associated with rare amino acid changes at 3 highly conserved residues; Gln to Pro at position 74 immediately N-terminal to the Rev activation domain, and Val to Leu and Ser to Pro at positions 104 and 106 at the Rev C-terminus, respectively. In D36, reduced Rev function was mapped to an unusual 13 amino acid extension at the Rev C-terminus. Conclusion These findings provide new genetic and mechanistic insights important for Rev function, and suggest that Rev function, not Rev/RRE binding may be rate limiting for HIV-1 replication. In addition, attenuated rev alleles may contribute to viral attenuation and long-term survival of HIV-1 infection in a subset of SBBC members.
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Affiliation(s)
- Melissa J Churchill
- The Macfarlane Burnet Institute for Medical Research and Public Health, Melbourne, Victoria, Australia
| | - Lisa Chiavaroli
- The Macfarlane Burnet Institute for Medical Research and Public Health, Melbourne, Victoria, Australia
| | - Steven L Wesselingh
- The Macfarlane Burnet Institute for Medical Research and Public Health, Melbourne, Victoria, Australia
- Department of Microbiology and Immunology, University of Melbourne, Melbourne, Victoria, Australia
- Department of Medicine, Monash University, Melbourne, Victoria, Australia
| | - Paul R Gorry
- The Macfarlane Burnet Institute for Medical Research and Public Health, Melbourne, Victoria, Australia
- Department of Microbiology and Immunology, University of Melbourne, Melbourne, Victoria, Australia
- Department of Medicine, Monash University, Melbourne, Victoria, Australia
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Chaloin L, Smagulova F, Hariton-Gazal E, Briant L, Loyter A, Devaux C. Potent inhibition of HIV-1 replication by backbone cyclic peptides bearing the Rev arginine rich motif. J Biomed Sci 2007; 14:565-84. [PMID: 17520355 DOI: 10.1007/s11373-007-9180-4] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/13/2006] [Accepted: 04/24/2007] [Indexed: 10/23/2022] Open
Abstract
Due to its essential role in the virus life cycle, the viral regulatory protein Rev constitutes an attractive target for the development of new antiviral molecules. In this work, a series of Backbone Cyclic Peptide (BCP) analogs that bear a conformationally constrained arginine rich motif (ARM) of Rev were tested for in vitro inhibition of HIV-1 replication. We observed a potent suppression of HIV-1 replication in chronically infected T lymphocytic cells treated with Rev-BCPs. We further investigated possible mechanisms of HIV-1 inhibition and showed that Rev-BCPs interfere slightly with the nuclear import process and are very efficient in blocking a mechanism that controls Pr55(gag) and gp160(env) synthesis. Interestingly, these protein precursors are known to be encoded by mRNAs that require Rev-binding for nuclear export. In situ hybridization using a Cy-3 conjugated HIV-1 gag oligonucleotide probe indicated that Rev-BCPs prevent the intracellular accumulation of unspliced viral RNA. As a model, the most promising analog, Rev-BCP 14, was studied by molecular modeling and dynamics in order to identify its binding site on the Rev Response Element (RRE). The annealing simulation suggests that upon binding on the RRE, Rev-BCP 14 widens the distorted major groove of the viral RNA. Numerous contacts between peptide and RNA were found within the complex and some were identified as key components for the interactions. Altogether, our data indicate that the use of conformationally constrained Rev-BCPs represents a promising strategy for the development of new peptide-based therapeutic agents against HIV-1.
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Affiliation(s)
- Laurent Chaloin
- Centre d'études d'agents Pathogènes et Biotechnologies pour la Santé (CPBS), Institut de Biologie, CNRS UMR5236-UM1-UM2, 4 Boulevard Henri IV, CS69033, 34965, Montpellier cedex 2, France.
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Anderson JL, Johnson AT, Howard JL, Purcell DFJ. Both linear and discontinuous ribosome scanning are used for translation initiation from bicistronic human immunodeficiency virus type 1 env mRNAs. J Virol 2007; 81:4664-76. [PMID: 17329338 PMCID: PMC1900145 DOI: 10.1128/jvi.01028-06] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Human immunodeficiency virus type 1 (HIV-1) generates 16 alternatively spliced isoforms of env mRNA that contain the same overlapping open reading frames for Vpu and Env proteins but differ in their 5' untranslated regions (UTR). A subset of env mRNAs carry the extra upstream Rev initiation codon in the 5' UTR. We explored the effect of the alternative UTR on the translation of Vpu and Env proteins from authentic env mRNAs expressed from cDNA constructs. Vpu expression from the subset of env mRNA isoforms with exons containing an upstream Rev AUG codon was minimal. However, every env mRNA isoform expressed similar levels of Env protein. Mutations that removed, altered the strength of, or introduced upstream AUG codons dramatically altered Vpu expression but had little impact on the consistent expression of Env. These data show that the different isoforms of env mRNA are not redundant but instead regulate Vpu production in HIV-1-infected cells. Furthermore, while the initiation of Vpu translation conforms to the leaky ribosome-scanning model, the consistent Env synthesis infers a novel, discontinuous ribosome-scanning mechanism to translate Env.
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Affiliation(s)
- Jenny L Anderson
- Department of Microbiology and Immunology, The University of Melbourne, Parkville 3010, Victoria, Australia
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Lévesque K, Halvorsen M, Abrahamyan L, Chatel-Chaix L, Poupon V, Gordon H, DesGroseillers L, Gatignol A, Mouland AJ. Trafficking of HIV-1 RNA is mediated by heterogeneous nuclear ribonucleoprotein A2 expression and impacts on viral assembly. Traffic 2007; 7:1177-93. [PMID: 17004321 DOI: 10.1111/j.1600-0854.2006.00461.x] [Citation(s) in RCA: 91] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
Few details are known about how the human immunodeficiency virus type 1 (HIV-1) genomic RNA is trafficked in the cytoplasm. Part of this process is controlled by the activity of heterogeneous nuclear ribonucleoprotein A2 (hnRNP A2). The role of hnRNP A2 during the expression of a bona fide provirus in HeLa cells is investigated in this study. Using immunofluorescence and fluorescence in situ hybridization techniques, we show that knockdown of hnRNP A2 expression in HIV-1-expressing cells results in the rapid accumulation of HIV-1 genomic RNA in a distinct, cytoplasmic space that corresponds to the microtubule-organizing center (MTOC). The RNA exits in the nucleus and accumulates at the MTOC region as a result of hnRNP A2 knockdown even during the expression of a provirus harboring mutations in the hnRNP A2-response element (A2RE), the expression of which results in nuclear retention of genomic RNA. We also demonstrate that hnRNP A2 expression is required for downstream trafficking of genomic RNA from the MTOC in the cytoplasm. Genomic RNA localization at the MTOC that was both the result of hnRNP A2 knockdown and the overexpression of Rab7-interacting lysosomal protein had little effect on pr55Gag synthesis but negatively influenced virus production and infectivity. These data indicate that altered HIV-1 genomic RNA localization modulates viral assembly and that the MTOC serves as a central site to which HIV-1 genomic RNA converges following its exit from the nucleus, with the host protein, hnRNP A2, playing a central role in taking it to and from this site in the cell.
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Affiliation(s)
- Kathy Lévesque
- HIV-1 RNA Trafficking Laboratory, 3755 Côte-Ste-Catherine Road, Montréal, Québec, Canada H3T 1E2
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Wolff H, Hartl A, Eilken HM, Hadian K, Ziegler M, Brack-Werner R. Live-cell assay for simultaneous monitoring of expression and interaction of proteins. Biotechniques 2007; 41:688, 690, 692. [PMID: 17191610 DOI: 10.2144/000112291] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022] Open
Affiliation(s)
- Horst Wolff
- Institute of Molecular Virology, GSF-National Research Center for Environment and Health, Neuherberg, Germany.
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Urcuqui-Inchima S, Castaño ME, Hernandez-Verdun D, St-Laurent G, Kumar A. Nuclear Factor 90, a cellular dsRNA binding protein inhibits the HIV Rev-export function. Retrovirology 2006; 3:83. [PMID: 17125513 PMCID: PMC1713252 DOI: 10.1186/1742-4690-3-83] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2006] [Accepted: 11/24/2006] [Indexed: 12/23/2022] Open
Abstract
BACKGROUND The HIV Rev protein is known to facilitate export of incompletely spliced and unspliced viral transcripts to the cytoplasm, a necessary step in virus life cycle. The Rev-mediated nucleo-cytoplasmic transport of nascent viral transcripts, dependents on interaction of Rev with the RRE RNA structural element present in the target RNAs. The C-terminal variant of dsRNA-binding nuclear protein 90 (NF90ctv) has been shown to markedly attenuate viral replication in stably transduced HIV-1 target cell line. Here we examined a mechanism of interference of viral life cycle involving Rev-NF90ctv interaction. RESULTS Since Rev:RRE complex formations depend on protein:RNA and protein:protein interactions, we investigated whether the expression of NF90ctv might interfere with Rev-mediated export of RRE-containing transcripts. When HeLa cells expressed both NF90ctv and Rev protein, we observed that NF90ctv inhibited the Rev-mediated RNA transport. In particular, three regions of NF90ctv protein are involved in blocking Rev function. Moreover, interaction of NF90ctv with the RRE RNA resulted in the expression of a reporter protein coding sequences linked to the RRE structure. Moreover, Rev influenced the subcellular localization of NF90ctv, and this process is leptomycin B sensitive. CONCLUSION The dsRNA binding protein, NF90ctv competes with HIV Rev function at two levels, by competitive protein:protein interaction involving Rev binding to specific domains of NF90ctv, as well as by its binding to the RRE-RNA structure. Our results are consistent with a model of Rev-mediated HIV-1 RNA export that envisions Rev-multimerization, a process interrupted by NF90ctv.
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Affiliation(s)
- Silvio Urcuqui-Inchima
- Grupo de Inmunovirología, Corporación Biogénesis, Universidad de Antioquia, A.A. 1226, Medellín, Colombia
| | - Maria Eugenia Castaño
- Grupo de Inmunovirología, Corporación Biogénesis, Universidad de Antioquia, A.A. 1226, Medellín, Colombia
| | - Danièle Hernandez-Verdun
- Institut Jacques Monod, CNRS, University Paris VI and Paris VII, 2 place Jussieu, 75251 Paris Cedex 05, France
| | - Georges St-Laurent
- Department of Biochemistry and Molecular Biology, The George Washington University, Washington, D.C. 20037, USA
| | - Ajit Kumar
- Department of Biochemistry and Molecular Biology, The George Washington University, Washington, D.C. 20037, USA
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Freed EO, Mouland AJ. The cell biology of HIV-1 and other retroviruses. Retrovirology 2006; 3:77. [PMID: 17083721 PMCID: PMC1635732 DOI: 10.1186/1742-4690-3-77] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/17/2006] [Accepted: 11/03/2006] [Indexed: 12/23/2022] Open
Abstract
In recognition of the growing influence of cell biology in retrovirus research, we recently organized a Summer conference sponsored by the American Society for Cell Biology (ASCB) on the Cell Biology of HIV-1 and other Retroviruses (July 20–23, 2006, Emory University, Atlanta, Georgia). The meeting brought together a number of leading investigators interested in the interplay between cell biology and retrovirology with an emphasis on presentation of new and unpublished data. The conference was arranged from early to late events in the virus replication cycle, with sessions on viral fusion, entry, and transmission; post-entry restrictions to retroviral infection; nuclear import and integration; gene expression/regulation of retroviral Gag and genomic RNA; and assembly/release. In this review, we will attempt to touch briefly on some of the highlights of the conference, and will emphasize themes and trends that emerged at the meeting.
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Affiliation(s)
- Eric O Freed
- Virus-Cell Interaction Section, HIV Drug Resistance Program, National Cancer Institute, Frederick, MD. 21702-1201, USA
| | - Andrew J Mouland
- HIV-1 RNA Trafficking Laboratory, Lady Davis Institute for Medical Research-Sir Mortimer B. Davis Jewish General Hospital, Departments of Medicine, Microbiology and Immunology, McGill University, Montréal, Québec, H3T 1E2, Canada
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Michienzi A, De Angelis FG, Bozzoni I, Rossi JJ. A nucleolar localizing Rev binding element inhibits HIV replication. AIDS Res Ther 2006; 3:13. [PMID: 16712721 PMCID: PMC1513592 DOI: 10.1186/1742-6405-3-13] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2006] [Accepted: 05/19/2006] [Indexed: 11/25/2022] Open
Abstract
The Rev protein of the human immunodeficiency virus (HIV) facilitates the nuclear export of intron containing viral mRNAs allowing formation of infectious virions. Rev traffics through the nucleolus and shuttles between the nucleus and cytoplasm. Rev multimerization and interaction with the export protein CRM1 takes place in the nucleolus. To test the importance of Rev nucleolar trafficking in the HIV-1 replication cycle, we created a nucleolar localizing Rev Response Element (RRE) decoy and tested this for its anti-HIV activity. The RRE decoy provided marked inhibition of HIV-1 replication in both the CEM T-cell line and in primary CD34+ derived monocytes. These results demonstrate that titration of Rev in the nucleolus impairs HIV-1 replication and supports a functional role for Rev trafficking in this sub-cellular compartment.
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Affiliation(s)
- Alessandro Michienzi
- Division of Molecular Biology, Beckman Research Institute of the City of Hope, 1450 East Duarte Rd., Duarte, California 91010, USA
- Present address: Istituto Superiore di Sanita', Department of Cell Biology and Neuroscience, Viale Regina Elena 299, 00161, Rome, Italy
| | - Fernanda G De Angelis
- Istituto Pasteur, Fondazione Cenci-Bolognetti, Department of Genetics and Molecular Biology, University of Rome La Sapienza and IBPM of CNR, Rome, Italy
| | - Irene Bozzoni
- Istituto Pasteur, Fondazione Cenci-Bolognetti, Department of Genetics and Molecular Biology, University of Rome La Sapienza and IBPM of CNR, Rome, Italy
| | - John J Rossi
- Division of Molecular Biology, Beckman Research Institute of the City of Hope, 1450 East Duarte Rd., Duarte, California 91010, USA
- Division of Molecular Biology, Graduate School of Biological Sciences, Beckman Research Institute of the City of Hope, 1450 E. Duarte Rd., Duarte, CA 91010, USA
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36
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Wolff H, Hadian K, Ziegler M, Weierich C, Kramer-Hammerle S, Kleinschmidt A, Erfle V, Brack-Werner R. Analysis of the influence of subcellular localization of the HIV Rev protein on Rev-dependent gene expression by multi-fluorescence live-cell imaging. Exp Cell Res 2006; 312:443-56. [PMID: 16368434 DOI: 10.1016/j.yexcr.2005.11.020] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2005] [Revised: 10/10/2005] [Accepted: 11/09/2005] [Indexed: 10/21/2022]
Abstract
The human immunodeficiency virus Rev protein is a post-transcriptional activator of HIV gene expression. Rev is a nucleocytoplasmic shuttle protein that displays characteristic nuclear/nucleolar subcellular localization in various cell lines. Cytoplasmic localization of Rev occurs under various conditions disrupting Rev function. The goal of this study was to investigate the relationship between localization of Rev and its functional activity in living cells. A triple-fluorescent imaging assay, called AQ-FIND, was established for automatic quantitative evaluation of nucleocytoplasmic distribution of fluorescently tagged proteins. This assay was used to screen 500 rev genes generated by error-prone PCR for Rev mutants with different localization phenotypes. Activities of the Rev mutants were determined with a second quantitative, dual-fluorescent reporter assay. In HeLa cells, the majority of nuclear Rev mutants had activities similar to wild-type Rev. The activities of Rev mutants with abnormal cytoplasmic localization ranged from moderately impaired to nonfunctional. There was no linear correlation between subcellular distribution and levels of Rev activity. In astrocytes, nuclear Rev mutants showed similar impaired activities as the cytoplasmic wild-type Rev. Our data suggest that steady-state subcellular localization is not a primary regulator of Rev activity but may change as a secondary consequence of altered Rev function. The methodologies described here have potential for studying the significance of subcellular localization for functions of other regulatory factors.
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MESH Headings
- Active Transport, Cell Nucleus
- Amino Acid Sequence
- Astrocytes/metabolism
- Astrocytes/virology
- Bacterial Proteins/genetics
- Bacterial Proteins/metabolism
- Cell Line, Tumor
- Cell Nucleus/metabolism
- Cytophotometry/methods
- Cytoplasm/metabolism
- Fatty Acids, Unsaturated/pharmacology
- Gene Expression Regulation, Viral
- Gene Products, gag/metabolism
- Gene Products, rev/genetics
- Gene Products, rev/metabolism
- Gene Products, rev/physiology
- HIV/genetics
- HIV/metabolism
- HeLa Cells
- Humans
- Image Processing, Computer-Assisted/methods
- Karyopherins/antagonists & inhibitors
- Luminescent Proteins/genetics
- Luminescent Proteins/metabolism
- Molecular Sequence Data
- Mutation/genetics
- Plasmids/genetics
- Protein Precursors/metabolism
- Receptors, Cytoplasmic and Nuclear/antagonists & inhibitors
- Sequence Homology, Amino Acid
- Transcriptional Activation/genetics
- Transfection
- Viral Structural Proteins/metabolism
- rev Gene Products, Human Immunodeficiency Virus
- Red Fluorescent Protein
- Exportin 1 Protein
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Affiliation(s)
- Horst Wolff
- Institute of Molecular Virology, GSF-National Research Center for Environment and Health, Ingolstaedterlandstr. 1, 85764 Neuherberg, Germany
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Strayer DS, Akkina R, Bunnell BA, Dropulic B, Planelles V, Pomerantz RJ, Rossi JJ, Zaia JA. Current status of gene therapy strategies to treat HIV/AIDS. Mol Ther 2005; 11:823-42. [PMID: 15922953 DOI: 10.1016/j.ymthe.2005.01.020] [Citation(s) in RCA: 74] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/24/2004] [Revised: 01/19/2005] [Accepted: 01/26/2005] [Indexed: 12/21/2022] Open
Abstract
Progress in developing effective gene transfer approaches to treat HIV-1 infection has been steady. Many different transgenes have been reported to inhibit HIV-1 in vitro. However, effective translation of such results to clinical practice, or even to animal models of AIDS, has been challenging. Among the reasons for this failure are uncertainty as to the most effective cell population(s) to target, the diffuseness of these target cells in the body, and ineffective or insufficiently durable gene delivery. Better understanding of the HIV-1 replicative cycle, host factors involved in HIV-1 infection, vector biology and application, transgene technology, animal models, and clinical study design have all contributed vastly to planning current and future strategies for application of gene therapeutic approaches to the treatment of AIDS. This review focuses on the newest developments in these areas and provides a strong basis for renewed optimism that gene therapy will have an important role to play in treating people infected with HIV-1.
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Affiliation(s)
- David S Strayer
- Department of Pathology, Jefferson Medical College, 1020 Locust Street, Room 251, Philadelphia, PA 19107, USA.
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38
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Phuphuakrat A, Auewarakul P. Functional variability of Rev response element in HIV-1 primary isolates. Virus Genes 2005; 30:23-9. [PMID: 15744559 DOI: 10.1007/s11262-004-4578-9] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Revised: 06/21/2004] [Accepted: 07/12/2004] [Indexed: 11/27/2022]
Abstract
We have previously studied sequence heterogeneity of HIV-1 Rev response element (RRE), and showed uneven variations in different stem-loops of both primary sequence and secondary structure. Here we studied the functional variation of RRE clones from a set of 10 primary isolates, and demonstrated a variation in the function of these RRE clones on the expression of Gag proteins from a truncated HIV-1 genome. The difference in Gag level was, in part, if not exclusively, resulted from the differential efficiency of RNA transport and enhancing of translation. These data suggested that variation of HIV-1 RRE may play a role in regulation of viral replication rate in HIV-1 primary isolates.
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Affiliation(s)
- Angsana Phuphuakrat
- Department of Microbiology, Faculty of Medicine Siriraj Hospital, Mahidol University, Bangkok, Thailand
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39
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Furnes C, Arnesen T, Askjaer P, Kjems J, Szilvay AM. HIV-1 Rev oligomerization is not obligatory in the presence of an extra basic domain. Retrovirology 2005; 2:39. [PMID: 15949040 PMCID: PMC1180471 DOI: 10.1186/1742-4690-2-39] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/25/2005] [Accepted: 06/10/2005] [Indexed: 12/02/2022] Open
Abstract
Background The HIV-1 Rev regulatory protein binds as an oligomeric complex to viral RNA mediating nuclear export of incompletely spliced and non-spliced viral mRNAs encoding the viral structural proteins. However, the biological significance of the obligatory complex formation of Rev upon the viral RNA is unclear. Results The activity of various fusion proteins based on the negative oligomerization-defect Rev mutant M4 was tested using Rev dependent reporter constructs. An artificial M4 mutant dimer and an M4 mutant containing an extra basic domain from the HTLV-I Rex protein exhibited nearly full activity when compared to wild type Rev. Conclusion Rev dimerization appears to be required to expose free basic domains whilst the Rev oligomeric complex remains bound to viral RNA via other basic domains.
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Affiliation(s)
- Clemens Furnes
- Department of Molecular Biology, University of Bergen, N-5020 Bergen, Norway
| | - Thomas Arnesen
- Department of Molecular Biology, University of Bergen, N-5020 Bergen, Norway
| | - Peter Askjaer
- Department of Molecular Biology, University of Aarhus, DK-8000, Aarhus C, Denmark
- EMBL, Heidelberg, Germany
| | - Jørgen Kjems
- Department of Molecular Biology, University of Aarhus, DK-8000, Aarhus C, Denmark
| | - Anne Marie Szilvay
- Department of Molecular Biology, University of Bergen, N-5020 Bergen, Norway
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40
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Fang J, Acheampong E, Dave R, Wang F, Mukhtar M, Pomerantz RJ. The RNA helicase DDX1 is involved in restricted HIV-1 Rev function in human astrocytes. Virology 2005; 336:299-307. [PMID: 15892970 DOI: 10.1016/j.virol.2005.03.017] [Citation(s) in RCA: 60] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2005] [Revised: 03/03/2005] [Accepted: 03/12/2005] [Indexed: 11/16/2022]
Abstract
Productive infection by human immunodeficiency virus type I (HIV-1) in the central nervous system (CNS) involves mainly macrophages and microglial cells. A frequency of less than 10% of human astrocytes is estimated to be infectable with HIV-1. Nonetheless, this relatively low percentage of infected astrocytes, but associated with a large total number of astrocytic cells in the CNS, makes human astrocytes a critical part in the analyses of potential HIV-1 reservoirs in vivo. Investigations in astrocytic cell lines and primary human fetal astrocytes revealed that limited HIV-1 replication in these cells resulted from low-level viral entry, transcription, viral protein processing, and virion maturation. Of note, a low ratio of unspliced versus spliced HIV-1-specific RNA was also investigated, as Rev appeared to act aberrantly in astrocytes, via loss of nuclear and/or nucleolar localization and diminished Rev-mediated function. Host cellular machinery enabling Rev function has become critical for elucidation of diminished Rev activity, especially for those factors leading to RNA metabolism. We have recently identified a DEAD-box protein, DDX1, as a Rev cellular co-factor and now have explored its potential importance in astrocytes. Cells were infected with HIV-1 pseudotyped with envelope glycoproteins of amphotropic murine leukemia viruses (MLV). Semi-quantitative reverse transcriptase-polymerase chain reactions (RT-PCR) for unspliced, singly-spliced, and multiply-spliced RNA clearly showed a lower ratio of unspliced/singly-spliced over multiply-spliced HIV-1-specific RNA in human astrocytes as compared to Rev-permissive, non-glial control cells. As well, the cellular localization of Rev in astrocytes was cytoplasmically dominant as compared to that of Rev-permissive, non-glial controls. This endogenous level of DDX1 expression in astrocytes was demonstrated directly to lead to a shift of Rev sub-cellular distribution dominance from nuclear and/or nucleolar to cytoplasmic, as input of exogenous DDX1 significantly altered both Rev sub-cellular localization from cytoplasmic to nuclear predominance and concomitantly increased HIV-1 viral production in these human astrocytes. We conclude that altered DDX1 expression in human astrocytes is, at least in part, responsible for the unfavorable cellular microenvironment for Rev function in these CNS-based cells. Thus, these data suggest a molecular mechanism(s) for restricted replication in astrocytes as a potential low-level site of residual HIV-1 in vivo.
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Affiliation(s)
- Jianhua Fang
- The Dorrance H. Hamilton Laboratories, Center for Human Virology and Biodefense, Division of Infectious Diseases and Environmental Medicine, Department of Medicine, Jefferson Medical College, Thomas Jefferson University, Philadelphia, PA 19107, USA
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41
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Kramer-Hämmerle S, Ceccherini-Silberstein F, Bickel C, Wolff H, Vincendeau M, Werner T, Erfle V, Brack-Werner R. Identification of a novel Rev-interacting cellular protein. BMC Cell Biol 2005; 6:20. [PMID: 15847701 PMCID: PMC1097722 DOI: 10.1186/1471-2121-6-20] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2004] [Accepted: 04/24/2005] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Human cell types respond differently to infection by human immunodeficiency virus (HIV). Defining specific interactions between host cells and viral proteins is essential in understanding how viruses exploit cellular functions and the innate strategies underlying cellular control of HIV replication. The HIV Rev protein is a post-transcriptional inducer of HIV gene expression and an important target for interaction with cellular proteins. Identification of Rev-modulating cellular factors may eventually contribute to the design of novel antiviral therapies. RESULTS Yeast-two hybrid screening of a T-cell cDNA library with Rev as bait led to isolation of a novel human cDNA product (16.4.1). 16.4.1-containing fusion proteins showed predominant cytoplasmic localization, which was dependent on CRM1-mediated export from the nucleus. Nuclear export activity of 16.4.1 was mapped to a 60 amino acid region and a novel transport signal identified. Interaction of 16.4.1 with Rev in human cells was shown in a mammalian two-hybrid assay and by colocalization of Rev and 16.4.1 in nucleoli, indicating that Rev can recruit 16.4.1 to the nucleus/nucleoli. Rev-dependent reporter expression was inhibited by overexpressing 16.4.1 and stimulated by siRNAs targeted to 16.4.1 sequences, demonstrating that 16.4.1 expression influences the transactivation function of Rev. CONCLUSION These results suggest that 16.4.1 may act as a modulator of Rev activity. The experimental strategies outlined in this study are applicable to the identification and biological characterization of further novel Rev-interacting cellular factors.
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Affiliation(s)
- Susanne Kramer-Hämmerle
- Institute of Molecular Virology, GSF-National Research Center for Environment and Health, Ingolstädter Landstraße 1, D-85764 Neuherberg, Germany
| | - Francesca Ceccherini-Silberstein
- Institute of Molecular Virology, GSF-National Research Center for Environment and Health, Ingolstädter Landstraße 1, D-85764 Neuherberg, Germany
- Department of Experimental Medicine, University of Rome Tor Vergata, Via Montpellier 1, Rome 00133, Italy
| | - Christian Bickel
- Institute of Molecular Virology, GSF-National Research Center for Environment and Health, Ingolstädter Landstraße 1, D-85764 Neuherberg, Germany
| | - Horst Wolff
- Institute of Molecular Virology, GSF-National Research Center for Environment and Health, Ingolstädter Landstraße 1, D-85764 Neuherberg, Germany
| | - Michelle Vincendeau
- Institute of Molecular Virology, GSF-National Research Center for Environment and Health, Ingolstädter Landstraße 1, D-85764 Neuherberg, Germany
| | - Thomas Werner
- Genomatix Software GmbH, Landsbergerstr. 6, D-80339 München, Germany
| | - Volker Erfle
- Institute of Molecular Virology, GSF-National Research Center for Environment and Health, Ingolstädter Landstraße 1, D-85764 Neuherberg, Germany
| | - Ruth Brack-Werner
- Institute of Molecular Virology, GSF-National Research Center for Environment and Health, Ingolstädter Landstraße 1, D-85764 Neuherberg, Germany
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Yu Z, Sánchez-Velar N, Catrina IE, Kittler ELW, Udofia EB, Zapp ML. The cellular HIV-1 Rev cofactor hRIP is required for viral replication. Proc Natl Acad Sci U S A 2005; 102:4027-32. [PMID: 15749819 PMCID: PMC552779 DOI: 10.1073/pnas.0408889102] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023] Open
Abstract
An important goal of contemporary HIV type 1 (HIV-1) research is to identify cellular cofactors required for viral replication. The HIV-1 Rev protein facilitates the cytoplasmic accumulation of the intron-containing viral gag-pol and env mRNAs and is required for viral replication. We have previously shown that a cellular protein, human Rev-interacting protein (hRIP), is an essential Rev cofactor that promotes the release of incompletely spliced HIV-1 RNAs from the perinuclear region. Here, we use complementary genetic approaches to ablate hRIP activity and analyze HIV-1 replication and viral RNA localization. We find that ablation of hRIP activity by a dominant-negative mutant or RNA interference inhibits virus production by mislocalizing Rev-directed RNAs to the nuclear periphery. We further show that depletion of endogenous hRIP by RNA interference results in the loss of viral replication in human cell lines and primary macrophages; virus production was restored to wild-type levels after reintroduction of hRIP protein. Taken together, our results indicate that hRIP is an essential cellular cofactor for Rev function and HIV-1 replication. Because hRIP is not required for cell viability, it may be an attractive target for the development of new antiviral strategies.
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Affiliation(s)
- Zhong Yu
- Program in Molecular Medicine and Center for AIDS Research (CFAR), University of Massachusetts Medical School, Worcester, MA 01605, USA
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Abstract
The cell nucleolus is the subnuclear body in which ribosomal subunits are assembled, and it is also the location of several processes not related to ribosome biogenesis. Recent studies have revealed that nucleolar components move about in a variety of ways. One class of movement is associated with ribosome assembly, which is a vectorial process originating at the sites of transcription in the border region between the fibrillar center and the dense fibrillar component. The nascent preribosomal particles move outwardly to become the granular components where further maturation takes place. These particles continue their travel through the nucleoplasm for eventual export to the cytoplasm to become functional ribosomes. In a second kind of motion, many nucleolar components rapidly exchange with the nucleoplasm. Thirdly, nucleolar components engage in very complex movements when the nucleolus disassembles at the beginning of mitosis and then reassembles at the end of mitosis. Finally, many other cellular and viral macromolecules, which are not related to ribosome assembly, also pass through or are retained by the nucleolus. These are involved in nontraditional roles of the nucleolus, including regulation of tumor suppressor and oncogene activities, signal recognition particle assembly, modification of small RNAs, control of aging, and modulating telomerase function.
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Affiliation(s)
- M O J Olson
- Department of Biochemistry, The University of Mississippi Medical Center, Jackson, MS 39216, USA.
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Nielsen MH, Pedersen FS, Kjems J. Molecular strategies to inhibit HIV-1 replication. Retrovirology 2005; 2:10. [PMID: 15715913 PMCID: PMC553987 DOI: 10.1186/1742-4690-2-10] [Citation(s) in RCA: 49] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2004] [Accepted: 02/16/2005] [Indexed: 11/10/2022] Open
Abstract
The human immunodeficiency virus type 1 (HIV-1) is the primary cause of the acquired immunodeficiency syndrome (AIDS), which is a slow, progressive and degenerative disease of the human immune system. The pathogenesis of HIV-1 is complex and characterized by the interplay of both viral and host factors. An intense global research effort into understanding the individual steps of the viral replication cycle and the dynamics during an infection has inspired researchers in the development of a wide spectrum of antiviral strategies. Practically every stage in the viral life cycle and every viral gene product is a potential target. In addition, several strategies are targeting host proteins that play an essential role in the viral life cycle. This review summarizes the main genetic approaches taken in such antiviral strategies.
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Affiliation(s)
- Morten Hjuler Nielsen
- Department of Molecular Biology, University of Aarhus, C.F. Møllers Alle, Bldg. 130, Room 404, DK-8000 Aarhus C, Denmark
| | - Finn Skou Pedersen
- Department of Molecular Biology, University of Aarhus, C.F. Møllers Alle, Bldg. 130, Room 404, DK-8000 Aarhus C, Denmark
| | - Jørgen Kjems
- Department of Molecular Biology, University of Aarhus, C.F. Møllers Alle, Bldg. 130, Room 404, DK-8000 Aarhus C, Denmark
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45
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Fang J, Kubota S, Yang B, Zhou N, Zhang H, Godbout R, Pomerantz RJ. A DEAD box protein facilitates HIV-1 replication as a cellular co-factor of Rev. Virology 2005; 330:471-80. [PMID: 15567440 DOI: 10.1016/j.virol.2004.09.039] [Citation(s) in RCA: 131] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2004] [Revised: 09/21/2004] [Accepted: 09/25/2004] [Indexed: 11/17/2022]
Abstract
HIV-1 Rev escorts unspliced viral mRNAs out of the nucleus of infected cells, which allows formation of infectious HIV-1 virions. We have identified a putative DEAD box (Asp-Glu-Ala-Asp) RNA helicase, DDX1, as a cellular co-factor of Rev, through yeast and mammalian two-hybrid systems using the N-terminal motif of Rev as "bait". DDX1 is not a functional homolog of HIV-1 Rev, but down-regulation of DDX1 resulted in an alternative splicing pattern of Rev-responsive element (RRE)-containing mRNA, and attenuation of Gag p24 antigen production from HLfb rev- cells rescued by exogenous Rev. Co-transfection of a DDX1 expression vector with HIV-1 significantly increased viral production. DDX1 binding to Rev, as well as to the RRE, strongly suggest that DDX1 affects Rev function through the Rev-RRE axis. Moreover, down-regulation of DDX1 altered the steady state subcellular distribution of Rev, from nuclear/nucleolar to cytoplasmic dominance. These findings indicate that DDX1 is a critical cellular co-factor for Rev function, which maintains the proper subcellular distribution of this lentiviral regulatory protein. Therefore, alterations in DDX1-Rev interactions could induce HIV-1 persistence and targeting DDX1 may lead to rationally designed and novel anti-HIV-1 strategies and therapeutics.
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Affiliation(s)
- Jianhua Fang
- Division of Infectious Diseases and Environmental Medicine, Department of Medicine, The Dorrance H. Hamilton Laboratories, Center for Human Virology and Biodefense, Jefferson Medical College, Thomas Jefferson University, Philadelphia, PA 19107, USA
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Bennett EM, Lever AML, Allen JF. Human immunodeficiency virus type 2 Gag interacts specifically with PRP4, a serine-threonine kinase, and inhibits phosphorylation of splicing factor SF2. J Virol 2004; 78:11303-12. [PMID: 15452250 PMCID: PMC521795 DOI: 10.1128/jvi.78.20.11303-11312.2004] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/08/2004] [Accepted: 06/10/2004] [Indexed: 11/20/2022] Open
Abstract
Using a yeast two-hybrid screen of a T-cell cDNA library to identify cellular proteins that bind to the human immunodeficiency virus type 2 (HIV-2) Gag polyprotein, we identified PRP4, a serine-threonine protein kinase. Specific interaction of PRP4 and HIV-2 Gag was confirmed in in vitro and in vivo assays. The interacting region of HIV-2 Gag is located in the conserved matrix and capsid domains, while both the RS (arginine-serine-rich) domain and the KS (kinase) domain of PRP4 are able to bind to HIV-2 Gag. PRP4 is not incorporated into virus particles. HIV-2 Gag is able to inhibit PRP4-mediated phosphorylation of the splicing factor SF2. This is also observed with Gag from simian immunodeficiency virus, a closely related virus, but not with Gag from human T-cell lymphotropic virus type 1. Our results provide evidence for a novel interaction between Gag and a cellular protein kinase involved in the control of constitutive splicing in two closely related retroviruses. We hypothesize that as Gag accumulates in the cell, down regulation of splicing occurs through reduced phosphorylation of SF2. At late stages of infection, this interaction may replace the function of the early viral regulatory protein Rev.
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Affiliation(s)
- Erin M Bennett
- Department of Medicine, Level 5, Addenbrooke's Hospital, Hills Road, Cambridge CB2 2QQ, United Kingdom
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Bériault V, Clément JF, Lévesque K, Lebel C, Yong X, Chabot B, Cohen EA, Cochrane AW, Rigby WFC, Mouland AJ. A late role for the association of hnRNP A2 with the HIV-1 hnRNP A2 response elements in genomic RNA, Gag, and Vpr localization. J Biol Chem 2004; 279:44141-53. [PMID: 15294897 DOI: 10.1074/jbc.m404691200] [Citation(s) in RCA: 47] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Two cis-acting RNA trafficking sequences (heterogenous ribonucleoprotein A2 (hnRNP A2)-response elements 1 and 2 or A2RE-1 and A2RE-2) have been identified in HIV-1 vpr and gag mRNAs and were found to confer cytoplasmic RNA trafficking in a murine oligodendrocyte assay. Their activities were assessed during HIV-1 proviral gene expression in COS7 cells. Single point mutations that were shown to severely block RNA trafficking were introduced into each of the A2REs. In both cases, this resulted in a marked decrease in hnRNP A2 binding to HIV-1 genomic RNA in whole cell extracts and hnRNP A2-containing polysomes. This also resulted in an accumulation of HIV-1 genomic RNA in the nucleus and a significant reduction in genomic RNA encapsidation levels. Immunofluorescence analyses revealed altered expression patterns for pr55Gag and particularly that for Vpr. Vpr localization became almost completely nuclear and this was reflected in a significant reduction in virion-associated Vpr levels. These effects coincided with late steps of the viral replication cycle and were not seen at early time points post-transfection. Transcription, splicing, steady state RNA levels, and pr55Gag processing were not affected. On the other hand, viral replication was markedly compromised in A2RE-2 mutant viruses and this correlated with lowered genomic RNA encapsidation levels. These data reveal new insights into the virus-host interactions between hnRNP A2 and the HIV-1 A2REs and their influence on the patterns of HIV-1 gene expression and viral assembly.
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Affiliation(s)
- Véronique Bériault
- HIV-1 RNA Trafficking Laboratory, Lady Davis Institute for Medical Research-Sir Mortimer B. Davis Jewish General Hospital, Room 323A, 3755 Côte-Ste-Catherine Road, Montréal, Québec H3T 1E2, Canada
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48
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Wu Y. HIV-1 gene expression: lessons from provirus and non-integrated DNA. Retrovirology 2004; 1:13. [PMID: 15219234 PMCID: PMC449739 DOI: 10.1186/1742-4690-1-13] [Citation(s) in RCA: 82] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/21/2004] [Accepted: 06/25/2004] [Indexed: 12/24/2022] Open
Abstract
Replication of HIV-1 involves a series of obligatory steps such as reverse transcription of the viral RNA genome into double-stranded DNA, and subsequent integration of the DNA into the human chromatin. Integration is an essential step for HIV-1 replication; yet the natural process of HIV-1 infection generates both integrated and high levels of non-integrated DNA. Although proviral DNA is the template for productive viral replication, the non-integrated DNA has been suggested to be active for limited viral gene synthesis. In this review, the regulation of viral gene expression from proviral DNA will be summarized and issues relating to non-integrated DNA as a template for transcription will be discussed, as will the possible function of pre-integration transcription in HIV-1 replication cycle.
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Affiliation(s)
- Yuntao Wu
- Center for Biodefense, Department of Molecular and Microbiology, George Mason University, Manassas, VA 20110, USA.
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Kimura T, Hashimoto I, Nagase T, Fujisawa JI. CRM1-dependent, but not ARE-mediated, nuclear export of IFN-alpha1 mRNA. J Cell Sci 2004; 117:2259-70. [PMID: 15126627 DOI: 10.1242/jcs.01076] [Citation(s) in RCA: 54] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
While the bulk of cellular mRNA is known to be exported by the TAP pathway, export of specific subsets of cellular mRNAs may rely on chromosome region maintenance 1 (CRM1). One line of evidence supporting this hypothesis comes from the study of mRNAs of certain early response genes (ERGs) containing the adenylate uridylate-rich element (ARE) in their 3' untranslated regions (3' UTRs). It was reported that HuR-mediated nuclear export of these mRNAs was CRM1-dependent under certain stress conditions. To further examine potential CRM1 pathways for other cellular mRNAs under stress conditions, the nuclear export of human interferon-alpha1 (IFN-alpha1) mRNA, an ERG mRNA induced upon viral infection, was studied. Overproduction of human immunodeficiency virus type 1 Rev protein reduced the expression level of the co-transfected IFN-alpha1 gene. This inhibitory effect, resulting from nuclear retention of IFN-alpha1 mRNA, was reversed when rev had a point mutation that made its nuclear export signal unable to associate with CRM1. Leptomycin B sensitivity experiments revealed that the cytoplasmic expression of IFN-alpha1 mRNA was arrested upon inhibition of CRM1. This finding was further supported by overexpression of DeltaCAN, a defective form of the nucleoporin Nup214/CAN that inhibits CRM1 in a dominant-negative manner, which resulted in the effective inhibition of IFN-alpha1 gene expression. Subsequent RNA fluorescence in situ hybridisation and immunocytochemistry demonstrated that the IFN-alpha1 mRNA was colocalised with CRM1, but not with TAP, in the nucleus. These results therefore imply that the nuclear export of IFN-alpha1 mRNA is mediated by CRM1. However, truncation of the 3' UTR did not negatively affect the nuclear export of IFN-alpha1 mRNA that lacked the ARE, unexpectedly indicating that this CRM1-dependent mRNA export may not be mediated via the ARE.
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Affiliation(s)
- Tominori Kimura
- Department of Microbiology, Kansai Medical University, Moriguchi, Osaka 570-8506, Japan
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Nguyen KL, llano M, Akari H, Miyagi E, Poeschla EM, Strebel K, Bour S. Codon optimization of the HIV-1 vpu and vif genes stabilizes their mRNA and allows for highly efficient Rev-independent expression. Virology 2004; 319:163-75. [PMID: 15015498 DOI: 10.1016/j.virol.2003.11.021] [Citation(s) in RCA: 136] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
Abstract
Two HIV-1 accessory proteins, Vpu and Vif, are notoriously difficult to express autonomously in the absence of the viral Tat and Rev proteins. We examined whether the codon bias observed in the vpu and vif genes relative to highly expressed human genes contributes to the Rev dependence and low expression level outside the context of the viral genome. The entire vpu gene as well as the 5' half of the vif gene were codon optimized and the resulting open reading frames (ORFs) (vphu and hvif, respectively) were cloned in autonomous expression vectors under the transcriptional control of the CMV promoter. Codon optimization efficiently removed the expression block observed in the native genes and allowed high levels of Rev- and Tat-independent expression of Vpu and Vif. Most of the higher protein levels detected are accounted for by enhanced steady-state levels of the mRNA encoding the optimized species. Nuclear run-on experiments show for the first time that codon optimization has no effect on the rate of transcriptional initiation or elongation of the vphu mRNA. Instead, optimization of the vpu gene was found to stabilize the vphu mRNA in the nucleus and enhance its export to the cytoplasm. This was achieved by allowing the optimized mRNA to use a new CRM I-independent nuclear export pathway. This work provides a better understanding of the molecular mechanisms underlying the process of codon optimization and introduces novel tools to study the biological functions of the Vpu and Vif proteins independently of other viral proteins.
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Affiliation(s)
- Kim-Lien Nguyen
- Viral Biochemistry Section, Laboratory of Molecular Microbiology, National Institutes of Allergy Diseases, Bethesda, MD 20892, USA
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