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Kawano K, Doucet AJ, Ueno M, Kariya R, An W, Marzetta F, Kuroki M, Turelli P, Sukegawa S, Okada S, Strebel K, Trono D, Ariumi Y. HIV-1 Vpr and p21 restrict LINE-1 mobility. Nucleic Acids Res 2019; 46:8454-8470. [PMID: 30085096 PMCID: PMC6144823 DOI: 10.1093/nar/gky688] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/12/2018] [Accepted: 07/18/2018] [Indexed: 01/12/2023] Open
Abstract
Long interspersed element-1 (LINE-1, L1) composes ∼17% of the human genome. However, genetic interactions between L1 and human immunodeficiency virus type 1 (HIV-1) remain poorly understood. In this study, we found that HIV-1 suppresses L1 retrotransposition. Notably, HIV-1 Vpr strongly inhibited retrotransposition without inhibiting L1 promoter activity. Since Vpr is known to regulate host cell cycle, we examined the possibility whether Vpr suppresses L1 retrotransposition in a cell cycle dependent manner. We showed that the inhibitory effect of a mutant Vpr (H71R), which is unable to arrest the cell cycle, was significantly relieved compared with that of wild-type Vpr, suggesting that Vpr suppresses L1 mobility in a cell cycle dependent manner. Furthermore, a host cell cycle regulator p21Waf1 strongly suppressed L1 retrotransposition. The N-terminal kinase inhibitory domain (KID) of p21 was required for this inhibitory effect. Another KID-containing host cell cycle regulator p27Kip1 also strongly suppressed L1 retrotransposition. We showed that Vpr and p21 coimmunoprecipitated with L1 ORF2p and they suppressed the L1 reverse transcriptase activity in LEAP assay, suggesting that Vpr and p21 inhibit ORF2p-mediated reverse transcription. Altogether, our results suggest that viral and host cell cycle regulatory machinery limit L1 mobility in cultured cells.
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Affiliation(s)
- Koudai Kawano
- Center for AIDS Research, Kumamoto University, Kumamoto 860-0811, Japan
| | - Aurélien J Doucet
- Institute for Research on Cancer and Aging, Nice (IRCAN), INSERM U1081, CNRS UMR 7284, Université de Nice-Sophia-Antipolis, Faculté de Médecine, 06107 Nice Cedex 2, France
| | - Mikinori Ueno
- Center for AIDS Research, Kumamoto University, Kumamoto 860-0811, Japan
| | - Ryusho Kariya
- Center for AIDS Research, Kumamoto University, Kumamoto 860-0811, Japan
| | - Wenfeng An
- Department of Pharmaceutical Sciences, South Dakota State University, Brookings, SD 57007, USA
| | - Flavia Marzetta
- School of Life Sciences, Ecole Polytechnique Fédérale de Lausanne, Lausanne CH-1015, Switzerland
| | - Misao Kuroki
- Center for AIDS Research, Kumamoto University, Kumamoto 860-0811, Japan
| | - Priscilla Turelli
- School of Life Sciences, Ecole Polytechnique Fédérale de Lausanne, Lausanne CH-1015, Switzerland
| | - Sayaka Sukegawa
- National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, Maryland 20892-0460, USA.,Clinical Research Center, Nagoya Medical Center, Nagoya 460-0001, Japan
| | - Seiji Okada
- Center for AIDS Research, Kumamoto University, Kumamoto 860-0811, Japan
| | - Klaus Strebel
- National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, Maryland 20892-0460, USA
| | - Didier Trono
- School of Life Sciences, Ecole Polytechnique Fédérale de Lausanne, Lausanne CH-1015, Switzerland
| | - Yasuo Ariumi
- Center for AIDS Research, Kumamoto University, Kumamoto 860-0811, Japan
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Ariumi Y. Multiple functions of DDX3 RNA helicase in gene regulation, tumorigenesis, and viral infection. Front Genet 2014; 5:423. [PMID: 25538732 PMCID: PMC4257086 DOI: 10.3389/fgene.2014.00423] [Citation(s) in RCA: 99] [Impact Index Per Article: 9.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2014] [Accepted: 11/19/2014] [Indexed: 12/11/2022] Open
Abstract
The DEAD-box RNA helicase DDX3 is a multifunctional protein involved in all aspects of RNA metabolism, including transcription, splicing, mRNA nuclear export, translation, RNA decay and ribosome biogenesis. In addition, DDX3 is also implicated in cell cycle regulation, apoptosis, Wnt-β-catenin signaling, tumorigenesis, and viral infection. Notably, recent studies suggest that DDX3 is a component of anti-viral innate immune signaling pathways. Indeed, DDX3 contributes to enhance the induction of anti-viral mediators, interferon (IFN) regulatory factor 3 and type I IFN. However, DDX3 seems to be an important target for several viruses, such as human immunodeficiency virus type 1 (HIV-1), hepatitis C virus (HCV), hepatitis B virus (HBV), and poxvirus. DDX3 interacts with HIV-1 Rev or HCV Core protein and modulates its function. At least, DDX3 is required for both HIV-1 and HCV replication. Therefore, DDX3 could be a novel therapeutic target for the development of drug against HIV-1 and HCV.
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Affiliation(s)
- Yasuo Ariumi
- Ariumi Project Laboratory, Center for AIDS Research - International Research Center for Medical Sciences, Kumamoto University Kumamoto, Japan
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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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4
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Yasuda-Inoue M, Kuroki M, Ariumi Y. Distinct DDX DEAD-box RNA helicases cooperate to modulate the HIV-1 Rev function. Biochem Biophys Res Commun 2013; 434:803-8. [PMID: 23608157 PMCID: PMC7092829 DOI: 10.1016/j.bbrc.2013.04.016] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/19/2013] [Accepted: 04/12/2013] [Indexed: 01/28/2023]
Abstract
Distinct DDX RNA helicases enhance the HIV-1 Rev function. Distinct DDX RNA helicases cooperate to enhance the Rev function. Several DDX RNA helicases except DDX6 interact with the Rev protein. DDX3 colocalizes with DDX5 and binds to it.
RNA helicase plays an important role in host mRNA and viral mRNA transcription, transport, and translation. Many viruses utilize RNA helicases in their life cycle, while human immunodeficiency virus type 1 (HIV-1) does not encode an RNA helicase. Thus, host RNA helicase has been involved in HIV-1 replication. Indeed, DDX1 and DDX3 DEAD-box RNA helicases are known to be required for efficient HIV-1 Rev-dependent RNA export. However, it remains unclear whether distinct DDX RNA helicases cross-talk and cooperate to modulate the HIV-1 Rev function. In this study, we noticed that distinct DDX RNA helicases, including DDX1, DDX3, DDX5, DDX17, DDX21, DDX56, except DDX6, bound to the Rev protein and they colocalized with Rev in nucleolus or nucleus. In this context, these DEAD-box RNA helicases except DDX6 markedly enhanced the HIV-1 Rev-dependent RNA export. Furthermore, DDX3 interacted with DDX5 and synergistically enhanced the Rev function. As well, combination of other distinct DDX RNA helicases cooperated to stimulate the Rev function. Altogether, these results suggest that distinct DDX DEAD-box RNA helicases cooperate to modulate the HIV-1 Rev function.
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Kumar S, Bose D, Suryawanshi H, Sabharwal H, Mapa K, Maiti S. Specificity of RSG-1.2 peptide binding to RRE-IIB RNA element of HIV-1 over Rev peptide is mainly enthalpic in origin. PLoS One 2011; 6:e23300. [PMID: 21853108 PMCID: PMC3154333 DOI: 10.1371/journal.pone.0023300] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2011] [Accepted: 07/12/2011] [Indexed: 02/03/2023] Open
Abstract
Rev is an essential HIV-1 regulatory protein which binds to the Rev responsive element (RRE) present within the env gene of HIV-1 RNA genome. This binding facilitates the transport of the RNA to the cytoplasm, which in turn triggers the switch between viral latency and active viral replication. Essential components of this complex have been localized to a minimal arginine rich Rev peptide and stem IIB region of RRE. A synthetic peptide known as RSG-1.2 binds with high binding affinity and specificity to the RRE-IIB than the Rev peptide, however the thermodynamic basis of this specificity has not yet been addressed. The present study aims to probe the thermodynamic origin of this specificity of RSG-1.2 over Rev Peptide for RRE-IIB. The temperature dependent melting studies show that RSG-1.2 binding stabilizes the RRE structure significantly (ΔTm = 4.3°C), in contrast to Rev binding. Interestingly the thermodynamic signatures of the binding have also been found to be different for both the peptides. At pH 7.5, RSG-1.2 binds RRE-IIB with a Ka = 16.2±0.6×107 M−1 where enthalpic change ΔH = −13.9±0.1 kcal/mol is the main driving force with limited unfavorable contribution from entropic change TΔS = −2.8±0.1 kcal/mol. A large part of ΔH may be due to specific stacking between U72 and Arg15. In contrast binding of Rev (Ka = 3.1±0.4×107 M−1) is driven mainly by entropy (ΔH = 0 kcal/mol and TΔS = 10.2±0.2 kcal/mol) which arises from major conformational changes in the RNA upon binding.
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Affiliation(s)
- Santosh Kumar
- Proteomics and Structural Biology Unit, Institute of Genomics and Integrative Biology, CSIR, Delhi, India
| | - Debojit Bose
- Proteomics and Structural Biology Unit, Institute of Genomics and Integrative Biology, CSIR, Delhi, India
| | - Hemant Suryawanshi
- Proteomics and Structural Biology Unit, Institute of Genomics and Integrative Biology, CSIR, Delhi, India
| | - Harshana Sabharwal
- Proteomics and Structural Biology Unit, Institute of Genomics and Integrative Biology, CSIR, Delhi, India
| | - Koyeli Mapa
- Proteomics and Structural Biology Unit, Institute of Genomics and Integrative Biology, CSIR, Delhi, India
| | - Souvik Maiti
- Proteomics and Structural Biology Unit, Institute of Genomics and Integrative Biology, CSIR, Delhi, India
- * E-mail:
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6
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Klase ZA, Van Duyne R, Kashanchi F. Identification of potential drug targets using genomics and proteomics: a systems approach. ADVANCES IN PHARMACOLOGY (SAN DIEGO, CALIF.) 2008; 56:327-68. [PMID: 18086417 DOI: 10.1016/s1054-3589(07)56011-4] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Affiliation(s)
- Zachary A Klase
- Department of Biochemistry, Medical Center, The George Washington University, Washington, DC 20037, USA
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7
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Mishra SH, Shelley CM, Barrow DJ, Darby MK, Germann MW. Solution structures and characterization of human immunodeficiency virus Rev responsive element IIB RNA targeting zinc finger proteins. Biopolymers 2006; 83:352-64. [PMID: 16826557 DOI: 10.1002/bip.20565] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
The Rev responsive element (RRE), a part of unspliced human immunodeficiency virus (HIV) RNA, serves a crucial role in the production of infectious HIV virions. The viral protein Rev binds to RRE and facilitates transport of mRNA to the cytoplasm. Inhibition of the Rev-RRE interaction disrupts the viral life cycle. Using a phage display protocol, dual zinc finger proteins (ZNFs) were generated that bind specifically to RREIIB at the high affinity Rev binding site. These proteins were further shortened and simplified, and they still retained their RNA binding affinity. The solution structures of ZNF29 and a mutant, ZNF29G29R, have been determined by nuclear magnetic resonance (NMR) spectroscopy. Both proteins form C(2)H(2)-type zinc fingers with essentially identical structures. RNA protein interactions were evaluated quantitatively by isothermal titration calorimetry, which revealed dissociation constants (K(d)'s) in the nanomolar range. The interaction with the RNA is dependent upon the zinc finger structure; in the presence of EDTA, RNA binding is abolished. For both proteins, RNA binding is mediated by the alpha-helical portion of the zinc fingers and target the bulge region of RREIIB-TR. However, ZNF29G29R exhibits significantly stronger binding to the RNA target than ZNF29; this illustrates that the binding of the zinc finger scaffold is amenable to further improvements.
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Affiliation(s)
- Subrata H Mishra
- Department of Chemistry, Georgia State University, Atlanta, 30303, USA
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8
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Kucerova L, Altanerova V, Altaner C, Boris-Lawrie K. Bovine leukemia virus structural gene vectors are immunogenic and lack pathogenicity in a rabbit model. J Virol 1999; 73:8160-6. [PMID: 10482566 PMCID: PMC112833 DOI: 10.1128/jvi.73.10.8160-8166.1999] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Infection with a replication-competent bovine leukemia virus structural gene vector (BLV SGV) is an innovative vaccination approach to prevent disease by complex retroviruses. Previously we developed BLV SGV that constitutively expresses BLV gag, pol, and env and related cis-acting sequences but lacks tax, rex, RIII, and GIV and most of the BLV long terminal repeat sequences, including the cis-acting Tax and Rex response elements. The novel SGV virus is replication competent and replicates a selectable vector to a titer similar to that of the parental BLV in cell culture. The overall goal of this study was to test the hypothesis that infection with BLV SGV is nonpathogenic in rabbits. BLV infection of rabbits by inoculation of cell-free BLV or cell-associated BLV typically causes an immunodeficiency-like syndrome and death by 1 year postinfection. We sought to evaluate whether in vivo transfection of BLV provirus recapitulates pathogenic BLV infection and to compare BLV and BLV SGV with respect to infection, immunogenicity, and clinical outcome. Three groups of rabbits were subjected to in vivo transfection with BLV, BLV SGV, or negative control DNA. The results of our 20-month study indicate that in vivo transfection of rabbits with BLV recapitulates the fatal BLV infection produced by cell-free or cell-associated BLV. The BLV-infected rabbits exhibited sudden onset of clinical decline and immunodeficiency-like symptoms that culminated in death. BLV and BLV SGV infected peripheral blood mononuclear cells and induced similar levels of seroconversion to BLV structural proteins. However, BLV SGV exhibited a reduced proviral load and did not trigger the immunodeficiency-like syndrome. These results are consistent with the hypothesis that BLV SGV is infectious and immunogenic and lacks BLV pathogenicity in rabbits, and they support the use of this modified proviral vector delivery system for vaccines against complex retroviruses like BLV.
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Affiliation(s)
- L Kucerova
- Cancer Research Institute, Slovak Academy of Sciences, SK-833 91 Bratislava, Slovakia
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9
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Friesen WJ, Darby MK. Specific RNA binding proteins constructed from zinc fingers. NATURE STRUCTURAL BIOLOGY 1998; 5:543-6. [PMID: 9665165 DOI: 10.1038/794] [Citation(s) in RCA: 34] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Abstract
A zinc finger library with degenerate alpha-helices was displayed on the surface of bacteriophage and proteins that bind human immunodeficiency virus type-1 (HIV-1) Rev response element stem loop IIB (RRE-IIB) RNA or 5S rRNA were isolated. DNA encoding affinity selected zinc fingers was shuffled by recombination in vitro to isolate proteins with higher RNA binding affinity. Proteins constructed in this way bind RNA specifically both in vitro and in vivo. These results demonstrate that RNA substrate specificity of zinc fingers can be changed through mutation of alpha-helices to construct novel RNA binding proteins.
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Affiliation(s)
- W J Friesen
- Department of Microbiology and Immunology, Kimmel Cancer Institute, Thomas Jefferson University, Philadelphia, Pennsylvania 19107, USA
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10
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Thomas SL, Oft M, Jaksche H, Casari G, Heger P, Dobrovnik M, Bevec D, Hauber J. Functional analysis of the human immunodeficiency virus type 1 Rev protein oligomerization interface. J Virol 1998; 72:2935-44. [PMID: 9525614 PMCID: PMC109739 DOI: 10.1128/jvi.72.4.2935-2944.1998] [Citation(s) in RCA: 55] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
The expression of human immunodeficiency virus type 1 (HIV-1) structural proteins requires the action of the viral trans-regulatory protein Rev. Rev is a nuclear shuttle protein that directly binds to its cis-acting Rev response element (RRE) RNA target sequence. Subsequent oligomerization of Rev monomers on the RRE and interaction of Rev with a cellular cofactor(s) result in the cytoplasmic accumulation of RRE-containing viral mRNAs. Moreover, Rev by itself is exported from the nucleus to the cytoplasm. Although it has been demonstrated that Rev multimerization is critically required for Rev activity and hence for HIV-1 replication, the number of Rev monomers required to form a trans-activation-competent complex on the RRE is unknown. Here we report a systematic analysis of the putative multimerization domains within the Rev trans-activator protein. We identify the amino acid residues which are part of the proposed single hydrophobic surface patch in the Rev amino terminus that mediates intermolecular interactions. Furthermore, we show that the expression of a multimerization-deficient Rev mutant blocks HIV-1 replication in a trans-dominant (dominant-negative) fashion.
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Affiliation(s)
- S L Thomas
- Department of Immunology, Novartis Research Institute, Vienna, Austria
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11
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Wentz MP, Moore BE, Cloyd MW, Berget SM, Donehower LA. A naturally arising mutation of a potential silencer of exon splicing in human immunodeficiency virus type 1 induces dominant aberrant splicing and arrests virus production. J Virol 1997; 71:8542-51. [PMID: 9343212 PMCID: PMC192318 DOI: 10.1128/jvi.71.11.8542-8551.1997] [Citation(s) in RCA: 46] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023] Open
Abstract
We have isolated a naturally arising human immunodeficiency type 1 (HIV-1) mutant containing a point mutation within the env gene. The point mutation resulted in complete loss of balanced splicing, with dominant production of aberrant mRNAs. The aberrant RNAs arose via activation of normally cryptic splice sites flanking the mutation within the env terminal exon to create exon 6D, which was subsequently incorporated in aberrant env, tat, rev, and nef mRNAs. Aberrant multiply spliced messages contributed to reduced virus replication as a result of a reduction in wild-type Rev protein. The point mutation within exon 6D activated exon 6D inclusion when the exon and its flanking splice sites were transferred to a heterologous minigene. Introduction of the point mutation into an otherwise wild-type HIV-1 proviral clone resulted in virus that was severely inhibited for replication in T cells and displayed elevated usage of exon 6D. Exon 6D contains a bipartite element similar to that seen in tat exon 3 of HIV-1, consisting of a potential exon splicing silencer (ESS) juxtaposed to a purine-rich sequence similar to known exon splicing enhancers. In the absence of a flanking 5' splice site, the point mutation within the exon 6D ESS-like element strongly activated env splicing, suggesting that the putative ESS plays a natural role in limiting the level of env splicing. We propose, therefore, that exon silencers may be a common element in the HIV-1 genome used to create balanced splicing of multiple products from a single precursor RNA.
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Affiliation(s)
- M P Wentz
- Division of Molecular Virology, Baylor College of Medicine, Houston, Texas 77030, USA
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12
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Powers MA, Forbes DJ, Dahlberg JE, Lund E. The vertebrate GLFG nucleoporin, Nup98, is an essential component of multiple RNA export pathways. J Cell Biol 1997; 136:241-50. [PMID: 9015297 PMCID: PMC2134807 DOI: 10.1083/jcb.136.2.241] [Citation(s) in RCA: 183] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/04/1996] [Revised: 11/21/1996] [Indexed: 02/03/2023] Open
Abstract
The 97-kD O-linked glycoprotein, Nup98, is a component of the Xenopus laevis nuclear pore complex and the only vertebrate GLFG nucleoporin identified (Powers, M.A., C. Macauley, F. Masiarz, and D.J. Forbes. 1995. J. Cell Biol. 128:721-736). We have investigated possible roles of xNup98 in the nucleocytoplasmic transport of proteins and RNAs by analyzing the consequences of injecting monospecific polyclonal antibodies to xNup98 into X. laevis oocytes. We show here that nuclear injection of anti-xNup98 inhibited the export of multiple classes of RNAs, including snRNAs, 5S RNA, large ribosomal RNAs, and mRNA. In contrast, the export of tRNA was unaffected. Injection of anti-xNup98 into the oocyte cytoplasm had no effect on export of any of the RNAs. Significantly, nuclear injection of anti-xNup98 antibodies did not inhibit import of either karyophilic proteins or snRNPs. This latter result is in agreement with our previous finding that Nup98 is not an essential element of the protein import pathway. Thus, Nup98 plays a role specifically in RNA export from the nucleus, and it appears to be an essential component of multiple RNA export pathways.
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Affiliation(s)
- M A Powers
- Department of Biology, University of California at San Diego, La Jolla 92093-0347, USA
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13
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Tan W, Schalling M, Zhao C, Luukkonen M, Nilsson M, Fenyö EM, Pavlakis GN, Schwartz S. Inhibitory activity of the equine infectious anemia virus major 5' splice site in the absence of Rev. J Virol 1996; 70:3645-58. [PMID: 8648699 PMCID: PMC190240 DOI: 10.1128/jvi.70.6.3645-3658.1996] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023] Open
Abstract
The major 5' splice site of equine infectious anemia virus (EIAV) conforms to the consensus 5' splice site in eight consecutive positions and is located immediately upstream of the gag AUG. Our results show that the presence of this 5' splice site on the EIAV gag mRNA decreases Gag production 30- to 60-fold. This is caused by inefficient nuclear mRNA export and inefficient mRNA utilization. Inhibition could be overcome by providing human immunodeficiency virus type 1 Rev/Rev-responsive element, human T-cell leukemia virus type 1 Rex/Rex-responsive element, or simian retrovirus type 1 constitutive transport element. In addition, inhibition could be abolished by introducing single point mutations in the 5' splice site or by moving the 5' splice site away from its natural position immediately upstream of the gag AUG. This demonstrates that both maintenance of a perfect consensus 5' splice site and its proper location on the mRNA are important for inhibitory activity of the EIAV major 5' splice site.
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Affiliation(s)
- W Tan
- Microbiology and Tumorbiology Center, Karolinska Institute, Stockholm, Sweden
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