1
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Lotfi S, Nasser H, Noyori O, Hiyoshi M, Takeuchi H, Koyanagi Y, Suzu S. M-Sec facilitates intercellular transmission of HIV-1 through multiple mechanisms. Retrovirology 2020; 17:20. [PMID: 32650782 PMCID: PMC7350586 DOI: 10.1186/s12977-020-00528-y] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/11/2020] [Accepted: 07/04/2020] [Indexed: 01/08/2023] Open
Abstract
Background HIV-1 promotes the formation of tunneling nanotubes (TNTs) that connect distant cells, aiding cell-to-cell viral transmission between macrophages. Our recent study suggests that the cellular protein M-Sec plays a role in these processes. However, the timing, mechanism, and to what extent M-Sec contributes to HIV-1 transmission is not fully understood, and the lack of a cell line model that mimics macrophages has hindered in-depth analysis. Results We found that HIV-1 increased the number, length and thickness of TNTs in a manner dependent on its pathogenic protein Nef and M-Sec in U87 cells, as observed in macrophages. In addition, we found that M-Sec was required not only for TNT formation but also motility of U87 cells, both of which are beneficial for viral transmission. In fact, M-Sec knockdown in U87 cells led to a significantly delayed viral production in both cellular and extracellular fractions. This inhibition was observed for wild-type virus, but not for a mutant virus lacking Nef, which is known to promote not only TNT formation but also migration of infected macrophages. Conclusions By taking advantage of useful features of U87 cells, we provided evidence that M-Sec mediates a rapid and efficient cell–cell transmission of HIV-1 at an early phase of infection by enhancing both TNT formation and cell motility.
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Affiliation(s)
- Sameh Lotfi
- Division of Infection & Hematopoiesis, Joint Research Center for Human Retrovirus Infection, Kumamoto University, Kumamoto, 860-0811, Japan.,International Research Center for Medical Sciences, Kumamoto University, Kumamoto, 860-0811, Japan
| | - Hesham Nasser
- Division of Infection & Hematopoiesis, Joint Research Center for Human Retrovirus Infection, Kumamoto University, Kumamoto, 860-0811, Japan.,International Research Center for Medical Sciences, Kumamoto University, Kumamoto, 860-0811, Japan.,Department of Clinical Pathology, Faculty of Medicine, Suez Canal University, Ismailia, 41511, Egypt
| | - Osamu Noyori
- Division of Infection & Hematopoiesis, Joint Research Center for Human Retrovirus Infection, Kumamoto University, Kumamoto, 860-0811, Japan.,International Research Center for Medical Sciences, Kumamoto University, Kumamoto, 860-0811, Japan
| | - Masateru Hiyoshi
- Department of Safety Research On Blood and Biological Products, National Institute of Infectious Diseases, Tokyo, 208-0011, Japan
| | - Hiroaki Takeuchi
- Department of Molecular Virology, Tokyo Medical and Dental University, Tokyo, 113-8519, Japan
| | - Yoshio Koyanagi
- Laboratory of Systems Virology, Institute for Frontier Life and Medical Sciences, Kyoto University, Kyoto University, KyotoKyoto, 606-8507, Japan
| | - Shinya Suzu
- Division of Infection & Hematopoiesis, Joint Research Center for Human Retrovirus Infection, Kumamoto University, Kumamoto, 860-0811, Japan.
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2
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Doi N, Koma T, Adachi A, Nomaguchi M. Expression Level of HIV-1 Vif Can Be Fluctuated by Natural Nucleotide Variations in the vif-Coding and Regulatory SA1D2prox Sequences of the Proviral Genome. Front Microbiol 2019; 10:2758. [PMID: 31849897 PMCID: PMC6893887 DOI: 10.3389/fmicb.2019.02758] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/06/2019] [Accepted: 11/12/2019] [Indexed: 11/26/2022] Open
Abstract
Vif is required for HIV-1 replication in natural target cells by counteracting host restriction factors, APOBEC3 (A3) proteins. We recently demonstrated that Vif expression level can be changed by naturally occurring single-nucleotide variations within SA1D2prox of the HIV-1 genome. We also found that levels for vif/vpr mRNAs are inversely correlated. While amino acid sequence per se is critical for functionality, Vif expression level modulated by signal sequences in its coding region is likely to be important as well. There are two splicing sites in the region involved in vpr expression. To reveal possible fluctuations of Vif-expression level, we examined SA1D2prox and vif gene by chimeric approaches using HIV-1 subtypes B and C with distinct anti-A3 activity. In this report, recombinant clones in subtype B backbone carrying chimeric sequences with respect to SA1D2prox/vif and those within the vif-coding region were generated. Of these, clones containing vif-coding sequence of subtype C, especially its 3′ region, expressed vif/Vif at a decreased level but did at an increased level for vpr/Vpr. Clones with reduced vif/Vif level grew similarly or slightly better than a parental clone in weakly A3G-positive cells but more poorly in highly A3G-expressing cells. Three clones with this property were also tested for their A3-degrading activity. One of the clones appeared to have some defect in addition to the poor ability to express vif/Vif. Taken all together, our results show that natural variations in the SA1D2prox and vif-coding region can change the Vif-expression level and affect the HIV-1 replication potential.
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Affiliation(s)
- Naoya Doi
- Department of Microbiology, Tokushima University Graduate School of Medical Science, Tokushima, Japan
| | - Takaaki Koma
- Department of Microbiology, Tokushima University Graduate School of Medical Science, Tokushima, Japan
| | - Akio Adachi
- Department of Microbiology, Kansai Medical University, Osaka, Japan
| | - Masako Nomaguchi
- Department of Microbiology, Tokushima University Graduate School of Medical Science, Tokushima, Japan
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3
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Murmann AE, Bartom ET, Schipma MJ, Vilker J, Chen S, Peter ME. 6mer Seed Toxicity in Viral microRNAs. iScience 2019; 23:100737. [PMID: 31838022 PMCID: PMC7033618 DOI: 10.1016/j.isci.2019.11.031] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/07/2019] [Revised: 11/13/2019] [Accepted: 11/15/2019] [Indexed: 12/19/2022] Open
Abstract
MicroRNAs (miRNAs) are short double-stranded noncoding RNAs (19-23 nucleotides) that regulate gene expression by suppressing mRNAs through RNA interference. Targeting is determined by the seed sequence (position 2-7/8) of the mature miRNA. A minimal G-rich seed of just six nucleotides is highly toxic to cells by targeting genes essential for cell survival. A screen of 215 miRNAs encoded by 17 human pathogenic viruses (v-miRNAs) now suggests that a number of v-miRNAs can kill cells through a G-rich 6mer sequence embedded in their seed. Specifically, we demonstrate that miR-K12-6-5p, an oncoviral mimic of the tumor suppressive miR-15/16 family encoded by human Kaposi sarcoma-associated herpes virus, harbors a noncanonical toxic 6mer seed (position 3-8) and that v-miRNAs are more likely than cellular miRNAs to utilize a noncanonical 6mer seed. Our data suggest that during evolution viruses evolved to use 6mer seed toxicity to kill cells. Tumor suppressive miR-15/16-5p with a toxic 6mer seed targets survival genes kshv-miR-K12-6-5p, a paralog of hsa-miR-15/16-5p carries an offset toxic 6mer seed A screen of 215 viral miRNAs identifies miRNAs that contain a toxic 6mer seed Many human viral miRNAs have the capacity to kill through 6mer seed toxicity
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Affiliation(s)
- Andrea E Murmann
- Division Hematology/Oncology, Department of Medicine, Northwestern University, Chicago, IL 60611, USA
| | - Elizabeth T Bartom
- Department of Biochemistry and Molecular Genetics, Northwestern University, Chicago, IL 60611, USA
| | - Matthew J Schipma
- Department of Biochemistry and Molecular Genetics, Northwestern University, Chicago, IL 60611, USA
| | - Jacob Vilker
- Division Hematology/Oncology, Department of Medicine, Northwestern University, Chicago, IL 60611, USA
| | - Siquan Chen
- Cellular Screening Center, Institute for Genomics & Systems Biology, The University of Chicago, Chicago, IL 60637, USA
| | - Marcus E Peter
- Division Hematology/Oncology, Department of Medicine, Northwestern University, Chicago, IL 60611, USA; Department of Biochemistry and Molecular Genetics, Northwestern University, Chicago, IL 60611, USA.
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4
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Nomaguchi M, Doi N, Yoshida T, Koma T, Adachi S, Ode H, Iwatani Y, Yokoyama M, Sato H, Adachi A. Production of HIV-1 vif mRNA Is Modulated by Natural Nucleotide Variations and SLSA1 RNA Structure in SA1D2prox Genomic Region. Front Microbiol 2017; 8:2542. [PMID: 29326677 PMCID: PMC5741601 DOI: 10.3389/fmicb.2017.02542] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2017] [Accepted: 12/07/2017] [Indexed: 12/11/2022] Open
Abstract
Genomic RNA of HIV-1 contains localized structures critical for viral replication. Its structural analysis has demonstrated a stem-loop structure, SLSA1, in a nearby region of HIV-1 genomic splicing acceptor 1 (SA1). We have previously shown that the expression level of vif mRNA is considerably altered by some natural single-nucleotide variations (nSNVs) clustering in SLSA1 structure. In this study, besides eleven nSNVs previously identified by us, we totally found nine new nSNVs in the SLSA1-containing sequence from SA1, splicing donor 2, and through to the start codon of Vif that significantly affect the vif mRNA level, and designated the sequence SA1D2prox (142 nucleotides for HIV-1 NL4-3). We then examined by extensive variant and mutagenesis analyses how SA1D2prox sequence and SLSA1 secondary structure are related to vif mRNA level. While the secondary structure and stability of SLSA1 was largely changed by nSNVs and artificial mutations introduced to restore the original NL4-3 form from altered ones by nSNVs, no clear association of the two SLSA1 properties with vif mRNA level was observed. In contrast, when naturally occurring SA1D2prox sequences that contain multiple nSNVs were examined, we attained significant inverse correlation between the vif level and SLSA1 stability. These results may suggest that SA1D2prox sequence adapts over time, and also that the altered SA1D2prox sequence, SLSA1 stability, and vif level are mutually related. In total, we show here that the entire SA1D2prox sequence and SLSA1 stability critically contribute to the modulation of vif mRNA level.
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Affiliation(s)
- Masako Nomaguchi
- Department of Microbiology, Graduate School of Medical Science, Tokushima University, Tokushima, Japan
| | - Naoya Doi
- Department of Microbiology, Graduate School of Medical Science, Tokushima University, Tokushima, Japan
| | - Tomoya Yoshida
- Department of Microbiology, Graduate School of Medical Science, Tokushima University, Tokushima, Japan
| | - Takaaki Koma
- Department of Microbiology, Graduate School of Medical Science, Tokushima University, Tokushima, Japan
| | - Shun Adachi
- Department of Microbiology, Graduate School of Medical Science, Tokushima University, Tokushima, Japan
| | - Hirotaka Ode
- Department of Infectious Diseases and Immunology, Clinical Research Center, National Hospital Organization Nagoya Medical Center, Nagoya, Japan
| | - Yasumasa Iwatani
- Department of Infectious Diseases and Immunology, Clinical Research Center, National Hospital Organization Nagoya Medical Center, Nagoya, Japan
| | - Masaru Yokoyama
- Laboratory of Viral Genomics, Pathogen Genomics Center, National Institute of Infectious Diseases, Tokyo, Japan
| | - Hironori Sato
- Laboratory of Viral Genomics, Pathogen Genomics Center, National Institute of Infectious Diseases, Tokyo, Japan
| | - Akio Adachi
- Department of Microbiology, Graduate School of Medical Science, Tokushima University, Tokushima, Japan
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5
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Abstract
The HIV genome encodes a small number of viral proteins (i.e., 16), invariably establishing cooperative associations among HIV proteins and between HIV and host proteins, to invade host cells and hijack their internal machineries. As a known example, the HIV envelope glycoprotein GP120 is closely associated with GP41 for viral entry. From a genome-wide perspective, a hypothesis can be worked out to determine whether 16 HIV proteins could develop 120 possible pairwise associations either by physical interactions or by functional associations mediated via HIV or host molecules. Here, we present the first systematic review of experimental evidence on HIV genome-wide protein associations using a large body of publications accumulated over the past 3 decades. Of 120 possible pairwise associations between 16 HIV proteins, at least 34 physical interactions and 17 functional associations have been identified. To achieve efficient viral replication and infection, HIV protein associations play essential roles (e.g., cleavage, inhibition, and activation) during the HIV life cycle. In either a dispensable or an indispensable manner, each HIV protein collaborates with another viral protein to accomplish specific activities that precisely take place at the proper stages of the HIV life cycle. In addition, HIV genome-wide protein associations have an impact on anti-HIV inhibitors due to the extensive cross talk between drug-inhibited proteins and other HIV proteins. Overall, this study presents for the first time a comprehensive overview of HIV genome-wide protein associations, highlighting meticulous collaborations between all viral proteins during the HIV life cycle.
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Affiliation(s)
- Guangdi Li
- Department of Metabolism and Endocrinology, Metabolic Syndrome Research Center, Key Laboratory of Diabetes Immunology, Ministry of Education, National Clinical Research Center for Metabolic Diseases, The Second Xiangya Hospital, Central South University, Changsha, Hunan, China KU Leuven-University of Leuven, Rega Institute for Medical Research, Department of Microbiology and Immunology, Leuven, Belgium
| | - Erik De Clercq
- KU Leuven-University of Leuven, Rega Institute for Medical Research, Department of Microbiology and Immunology, Leuven, Belgium
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6
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HIV Genome-Wide Protein Associations: a Review of 30 Years of Research. Microbiol Mol Biol Rev 2016; 80:679-731. [PMID: 27357278 DOI: 10.1128/mmbr.00065-15] [Citation(s) in RCA: 50] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Abstract
The HIV genome encodes a small number of viral proteins (i.e., 16), invariably establishing cooperative associations among HIV proteins and between HIV and host proteins, to invade host cells and hijack their internal machineries. As a known example, the HIV envelope glycoprotein GP120 is closely associated with GP41 for viral entry. From a genome-wide perspective, a hypothesis can be worked out to determine whether 16 HIV proteins could develop 120 possible pairwise associations either by physical interactions or by functional associations mediated via HIV or host molecules. Here, we present the first systematic review of experimental evidence on HIV genome-wide protein associations using a large body of publications accumulated over the past 3 decades. Of 120 possible pairwise associations between 16 HIV proteins, at least 34 physical interactions and 17 functional associations have been identified. To achieve efficient viral replication and infection, HIV protein associations play essential roles (e.g., cleavage, inhibition, and activation) during the HIV life cycle. In either a dispensable or an indispensable manner, each HIV protein collaborates with another viral protein to accomplish specific activities that precisely take place at the proper stages of the HIV life cycle. In addition, HIV genome-wide protein associations have an impact on anti-HIV inhibitors due to the extensive cross talk between drug-inhibited proteins and other HIV proteins. Overall, this study presents for the first time a comprehensive overview of HIV genome-wide protein associations, highlighting meticulous collaborations between all viral proteins during the HIV life cycle.
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7
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Bashir T, Patgaonkar M, Kumar C S, Pasi A, Reddy KVR. HbAHP-25, an In-Silico Designed Peptide, Inhibits HIV-1 Entry by Blocking gp120 Binding to CD4 Receptor. PLoS One 2015; 10:e0124839. [PMID: 25915507 PMCID: PMC4411102 DOI: 10.1371/journal.pone.0124839] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2014] [Accepted: 03/18/2015] [Indexed: 11/18/2022] Open
Abstract
Human Immunodeficiency Virus (HIV-1) poses a serious threat to the developing world and sexual transmission continues to be the major source of new infections. Therefore, the development of molecules, which prevent new HIV-1 infections, is highly warranted. In the present study, a panel of human hemoglobin (Hb)-α subunit derived peptides and their analogues, with an ability to bind gp120, were designed in-silico and their anti-HIV-1 activity was evaluated. Of these peptides, HbAHP-25, an analogue of Hb-α derived peptide, demonstrated significant anti-HIV-1 activity. HbAHP-25 was found to be active against CCR5-tropic HIV-1 strains (ADA5 and BaL) and CXCR4-tropic HIV-1 strains (IIIB and NL4-3). Surface plasmon resonance (SPR) and ELISA revealed direct interaction between HbAHP-25 and HIV-1 envelope protein, gp120. The peptide prevented binding of CD4 to gp120 and blocked subsequent steps leading to entry and/or fusion or both. Anti-HIV activity of HbAHP-25 appeared to be specific as it failed to inhibit the entry of HIV-1 pseudotyped virus (HIV-1 VSV). Further, HbAHP-25 was found to be non-cytotoxic to TZM-bl cells, VK2/E6E7 cells, CEM-GFP cells and PBMCs, even at higher concentrations. Moreover, HbAHP-25 retained its anti-HIV activity in presence of seminal plasma and vaginal fluid. In brief, the study identified HbAHP-25, a novel anti-HIV peptide, which directly interacts with gp120 and thus has a potential to inhibit early stages of HIV-1 infection.
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Affiliation(s)
- Tahir Bashir
- Division of Molecular Immunology and Microbiology, National Institute for Research in Reproductive Health, Indian Council of Medical Research, Mumbai, India
| | - Mandar Patgaonkar
- Department of Biological Sciences, Tata Institute for Fundamental Research, Mumbai, India
| | - Selvaa Kumar C
- Department of Bioinformatics, School of Biotechnology and Bioinformatics, D.Y. Patil University, Navi Mumbai, India
| | - Achhelal Pasi
- Division of Molecular Immunology and Microbiology, National Institute for Research in Reproductive Health, Indian Council of Medical Research, Mumbai, India
| | - Kudumula Venkata Rami Reddy
- Division of Molecular Immunology and Microbiology, National Institute for Research in Reproductive Health, Indian Council of Medical Research, Mumbai, India
- * E-mail:
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8
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c-Src and Pyk2 Protein Tyrosine Kinases Play Protective Roles in Early HIV-1 Infection of CD4+ T-Cell Lines. J Acquir Immune Defic Syndr 2014; 66:118-26. [DOI: 10.1097/qai.0000000000000105] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
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9
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Bell NM, L'Hernault A, Murat P, Richards JE, Lever AML, Balasubramanian S. Targeting RNA-protein interactions within the human immunodeficiency virus type 1 lifecycle. Biochemistry 2013; 52:9269-74. [PMID: 24358934 PMCID: PMC3928988 DOI: 10.1021/bi401270d] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
![]()
RNA–protein
interactions are vital throughout the HIV-1
life cycle for the successful production of infectious virus particles.
One such essential RNA–protein interaction occurs between the
full-length genomic viral RNA and the major structural protein of
the virus. The initial interaction is between the Gag polyprotein
and the viral RNA packaging signal (psi or Ψ), a highly conserved
RNA structural element within the 5′-UTR of the HIV-1 genome,
which has gained attention as a potential therapeutic target. Here,
we report the application of a target-based assay to identify small
molecules, which modulate the interaction between Gag and Ψ.
We then demonstrate that one such molecule exhibits potent inhibitory
activity in a viral replication assay. The mode of binding of the
lead molecules to the RNA target was characterized by 1H NMR spectroscopy.
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Affiliation(s)
- Neil M Bell
- Department of Chemistry, University of Cambridge , Lensfield Road, Cambridge, CB2 1EW, U.K
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10
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A noncanonical mu-1A-binding motif in the N terminus of HIV-1 Nef determines its ability to downregulate major histocompatibility complex class I in T lymphocytes. J Virol 2012; 86:3944-51. [PMID: 22301137 DOI: 10.1128/jvi.06257-11] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Downregulation of major histocompatibility complex class I (MHC-I) by HIV-1 Nef protein is indispensable for evasion of protective immunity by HIV-1. Though it has been suggested that the N-terminal region of Nef contributes to the function by associating with a mu-1A subunit of adaptor protein 1, the structural basis of the interaction between Nef and mu-1A remains elusive. We found that a tripartite hydrophobic motif (Trp13/Val16/Met20) in the N terminus of Nef was required for the MHC-I downregulation. Importantly, the motif functioned as a noncanonical mu-1A-binding motif for the interaction with the tyrosine motif-binding site of the mu-1A subunit. Our findings will help understanding of how HIV-1 evades the antiviral immune response by selectively redirecting the cellular protein trafficking system.
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11
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Chutiwitoonchai N, Hiyoshi M, Mwimanzi P, Ueno T, Adachi A, Ode H, Sato H, Fackler OT, Okada S, Suzu S. The identification of a small molecule compound that reduces HIV-1 Nef-mediated viral infectivity enhancement. PLoS One 2011; 6:e27696. [PMID: 22110726 PMCID: PMC3217016 DOI: 10.1371/journal.pone.0027696] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2011] [Accepted: 10/22/2011] [Indexed: 12/14/2022] Open
Abstract
Nef is a multifunctional HIV-1 protein that accelerates progression to AIDS, and enhances the infectivity of progeny viruses through a mechanism that is not yet understood. Here, we show that the small molecule compound 2c reduces Nef-mediated viral infectivity enhancement. When added to viral producer cells, 2c did not affect the efficiency of viral production itself. However, the infectivity of the viruses produced in the presence of 2c was significantly lower than that of control viruses. Importantly, an inhibitory effect was observed with Nef(+) wild-type viruses, but not with viruses produced in the absence of Nef or in the presence of proline-rich PxxP motif-disrupted Nef, both of which displayed significantly reduced intrinsic infectivity. Meanwhile, the overexpression of the SH3 domain of the tyrosine kinase Hck, which binds to a PxxP motif in Nef, also reduced viral infectivity. Importantly, 2c inhibited Hck SH3-Nef binding, which was more marked when Nef was pre-incubated with 2c prior to its incubation with Hck, indicating that both Hck SH3 and 2c directly bind to Nef and that their binding sites overlap. These results imply that both 2c and the Hck SH3 domain inhibit the interaction of Nef with an unidentified host protein and thereby reduce Nef-mediated infectivity enhancement. The first inhibitory compound 2c is therefore a valuable chemical probe for revealing the underlying molecular mechanism by which Nef enhances the infectivity of HIV-1.
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Affiliation(s)
| | | | - Philip Mwimanzi
- Center for AIDS Research, Kumamoto University, Kumamoto, Japan
| | - Takamasa Ueno
- Center for AIDS Research, Kumamoto University, Kumamoto, Japan
| | - Akio Adachi
- Department of Microbiology, Institute of Health Biosciences, The University of Tokushima Graduate School, Tokushima, Japan
| | - Hirotaka Ode
- Pathogen Genomics Center, National Institute of Infectious Diseases, Tokyo, Japan
| | - Hironori Sato
- Pathogen Genomics Center, National Institute of Infectious Diseases, Tokyo, Japan
| | - Oliver T. Fackler
- Department of Infectious Diseases, Virology, University of Heidelberg, Heidelberg, Germany
| | - Seiji Okada
- Center for AIDS Research, Kumamoto University, Kumamoto, Japan
| | - Shinya Suzu
- Center for AIDS Research, Kumamoto University, Kumamoto, Japan
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12
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T cell-based functional cDNA library screening identified SEC14-like 1a carboxy-terminal domain as a negative regulator of human immunodeficiency virus replication. Vaccine 2010; 28 Suppl 2:B68-74. [DOI: 10.1016/j.vaccine.2009.07.084] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2009] [Revised: 07/07/2009] [Accepted: 07/24/2009] [Indexed: 11/19/2022]
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13
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Piroozmand A, Yamamoto Y, Khamsri B, Fujita M, Uchiyama T, Adachi A. Generation and characterization of APOBEC3G-positive 293T cells for HIV-1 Vif study. THE JOURNAL OF MEDICAL INVESTIGATION 2007; 54:154-8. [PMID: 17380027 DOI: 10.2152/jmi.54.154] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022]
Abstract
We have established a number of 293T cell lines that express a human anti HIV-1 factor APOBEC3G. Out of seven cell clones examined, four were readily demonstrated to express APOBEC3G by immunoblotting analysis. In particular, two clones (A3G-C1 and -C4) were found to produce a much higher level of functional APOBEC3G relative to that by pooled cell clones. The transfection efficiency of all these cell clones were similar to that of the parental cells, producing a comparable level of virions upon transfection of wild type and vif-minus proviral DNA clones. Furthermore, the expression level of APOBEC3G in the best cell line (A3G-C1) was far much higher than those of an APOBEC3G-positive lymphocyte cell line and peripheral blood mononuclear cells. We finally monitored the incorporation of APOBEC3G into virions produced in A3G-C1. APOBEC3G was easily detected in progeny viral particles upon transfection of vif-minus proviral clone but not of wild type. These results indicated that our new A3G-C1 cell line is eminently useful for various studies on the interaction of human APOBEC3G and HIV-1 Vif.
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Affiliation(s)
- Ahmad Piroozmand
- Department of Virology, Institute of Health Biosciences, The University of Tokushima Graduate School, Tokushima, Japan
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14
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Costa LJ, Chen N, Lopes A, Aguiar RS, Tanuri A, Plemenitas A, Peterlin BM. Interactions between Nef and AIP1 proliferate multivesicular bodies and facilitate egress of HIV-1. Retrovirology 2006; 3:33. [PMID: 16764724 PMCID: PMC1526754 DOI: 10.1186/1742-4690-3-33] [Citation(s) in RCA: 47] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/05/2006] [Accepted: 06/09/2006] [Indexed: 12/13/2022] Open
Abstract
Background Nef is an accessory protein of primate lentiviruses, HIV-1, HIV-2 and SIV. Besides removing CD4 and MHC class I from the surface and activating cellular signaling cascades, Nef also binds GagPol during late stages of the viral replicative cycle. In this report, we investigated further the ability of Nef to facilitate the replication of HIV-1. Results To this end, first the release of new viral particles was much lower in the absence of Nef in a T cell line. Since the same results were obtained in the absence of the viral envelope using pseudo-typed viruses, this phenomenon was independent of CD4 and enhanced infectivity. Next, we found that Nef not only possesses a consensus motif for but also binds AIP1 in vitro and in vivo. AIP1 is the critical intermediate in the formation of multivesicular bodies (MVBs), which play an important role in the budding and release of viruses from infected cells. Indeed, Nef proliferated MVBs in cells, but only when its AIP1-binding site was intact. Finally, these functions of Nef were reproduced in primary macrophages, where the wild type but not mutant Nef proteins led to increased release of new viral particles from infected cells. Conclusion We conclude that by binding GagPol and AIP1, Nef not only proliferates MVBs but also contributes to the egress of viral particles from infected cells.
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Affiliation(s)
- Luciana J Costa
- Molecular Virology Laboratory, Dep. of Genetics, Federal University of Rio de Janeiro, Rio de Janeiro, Brazil
| | - Nan Chen
- Departments of Medicine, Microbiology and Immunology, Rosalind Russell Medical Research Center, University of California at San Francisco, San Francisco, CA, USA
| | - Adriana Lopes
- Molecular Virology Laboratory, Dep. of Genetics, Federal University of Rio de Janeiro, Rio de Janeiro, Brazil
| | - Renato S Aguiar
- Molecular Virology Laboratory, Dep. of Genetics, Federal University of Rio de Janeiro, Rio de Janeiro, Brazil
| | - Amilcar Tanuri
- Molecular Virology Laboratory, Dep. of Genetics, Federal University of Rio de Janeiro, Rio de Janeiro, Brazil
| | - Ana Plemenitas
- Institute of Biochemistry, Faculty of Medicine, University of Ljubljana, Ljubljana, Slovenia
| | - B Matija Peterlin
- Departments of Medicine, Microbiology and Immunology, Rosalind Russell Medical Research Center, University of California at San Francisco, San Francisco, CA, USA
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15
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Chen H, Lilley CE, Yu Q, Lee DV, Chou J, Narvaiza I, Landau NR, Weitzman MD. APOBEC3A Is a Potent Inhibitor of Adeno-Associated Virus and Retrotransposons. Curr Biol 2006; 16:480-5. [PMID: 16527742 DOI: 10.1016/j.cub.2006.01.031] [Citation(s) in RCA: 281] [Impact Index Per Article: 15.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2005] [Revised: 01/09/2006] [Accepted: 01/10/2006] [Indexed: 01/21/2023]
Abstract
APOBEC3 proteins constitute a family of cytidine deaminases that provide intracellular resistance to retrovirus replication and transposition of endogenous retroelements. One family member, APOBEC3A (hA3A), is an orphan, without any known antiviral activity. We show that hA3A is catalytically active and that it, but none of the other family members, potently inhibits replication of the parvovirus adeno-associated virus (AAV). hA3A was also a potent inhibitor of the endogenous LTR retroelements, MusD, IAP, and the non-LTR retroelement, LINE-1. Its function was dependent on the conserved amino acids of the hA3A active site, consistent with a role for cytidine deamination, although mutations in retroelement sequences were not found. These findings demonstrate the potent activity of hA3A, an APOBEC3 family member with no previously identified function. They also highlight the functional differences between APOBEC3 proteins. The APOBEC3 family members have distinct functions and may have evolved to resist various classes of genetic elements.
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Affiliation(s)
- Hui Chen
- Infectious Disease Laboratory, The Salk Institute for Biological Studies, 10010 North Torrey Pines Road, La Jolla, California 92037, USA
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16
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Wang H, Sakurai A, Khamsri B, Uchiyama T, Gu H, Adachi A, Fujita M. Unique characteristics of HIV-1 Vif expression. Microbes Infect 2005; 7:385-90. [PMID: 15784183 DOI: 10.1016/j.micinf.2004.11.010] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2004] [Revised: 11/12/2004] [Accepted: 11/12/2004] [Indexed: 11/16/2022]
Abstract
We examined the steady-state expression in cells of four accessory proteins of human immunodeficiency virus type 1 (HIV-1). For this purpose, a series of single gene expression vectors for these viral proteins were constructed and were monitored for their production by transfection. Among them, the expression level of Vif was found to be lowest in both the absence and presence of APOBEC3G. In addition, we noticed the presence of its truncated form, which was not observed for the other accessory proteins. When a subgenomic vector was used for transfection, authentic and several small forms of Vif were produced. By mutational analysis, these forms were demonstrated to be mutant Vif proteins translated from M8, M16 and M29. When a full-length molecular clone was used, the smaller versions of Vif were hardly observed. Functional analysis of these mutant Vif proteins showed that they are incapable of modulating viral infectivity. The results described above, i.e. the low steady-state expression and the presence of truncated forms, represent the unique characteristics of HIV-1 Vif.
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Affiliation(s)
- Huaqing Wang
- Department of Microbiology, Harbin Medical University, Harbin 150086, People's Republic of China
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17
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Akari H, Fujita M, Kao S, Khan MA, Shehu-Xhilaga M, Adachi A, Strebel K. High level expression of human immunodeficiency virus type-1 Vif inhibits viral infectivity by modulating proteolytic processing of the Gag precursor at the p2/nucleocapsid processing site. J Biol Chem 2004; 279:12355-62. [PMID: 14722068 DOI: 10.1074/jbc.m312426200] [Citation(s) in RCA: 53] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The human immunodeficiency virus type-1 Vif protein has a crucial role in regulating viral infectivity. However, we found that newly synthesized Vif is rapidly degraded by cellular proteases. We tested the dose dependence of Vif in non-permissive H9 cells and found that Vif, when expressed at low levels, increased virus infectivity in a dose-dependent manner. Surprisingly, however, the range of Vif required for optimal virus infectivity was narrow, and further increases in Vif severely reduced viral infectivity. Inhibition of viral infectivity at higher levels of Vif was cell type-independent and was associated with an accumulation of Gag-processing intermediates. Vif did not act as a general protease inhibitor but selectively inhibited Gag processing at the capsid and nucleocapsid (NC) boundary. Identification of Vif variants that were efficiently packaged but were unable to modulate Gag processing suggests that Vif packaging was necessary but insufficient for the production of 33- and 34-kDa processing intermediates. Interestingly, these processing intermediates, like Vif, associated with viral nucleoprotein complexes more rigidly than mature capsid and NC. We conclude that virus-associated Vif inhibits processing of a subset of Gag precursor molecules at the p2/NC primary cleavage site. Modulation of processing of a small subset of Gag molecules by physiological levels of Vif may be important for virus maturation. However, the accumulation of such processing intermediates at high levels of Vif is inhibitory. Thus, rapid intracellular degradation of Vif may have evolved as a mechanism to prevent such inhibitory effects of Vif.
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Affiliation(s)
- Hirofumi Akari
- Laboratory of Molecular Microbiology, NIAID, National Institutes of Health, 4/312, 4 Center Drive, MSC 0460, Bethesda, MD 20892-0460, USA
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18
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Kao S, Khan MA, Miyagi E, Plishka R, Buckler-White A, Strebel K. The human immunodeficiency virus type 1 Vif protein reduces intracellular expression and inhibits packaging of APOBEC3G (CEM15), a cellular inhibitor of virus infectivity. J Virol 2003; 77:11398-407. [PMID: 14557625 PMCID: PMC229358 DOI: 10.1128/jvi.77.21.11398-11407.2003] [Citation(s) in RCA: 253] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023] Open
Abstract
Replication of human immunodeficiency virus type 1 (HIV-1) in most primary cells and some immortalized T-cell lines depends on the activity of the viral infectivity factor (Vif). Vif has the ability to counteract a cellular inhibitor, recently identified as CEM15, that blocks infectivity of Vif-defective HIV-1 variants. CEM15 is identical to APOBEC3G and belongs to a family of proteins involved in RNA and DNA deamination. We cloned APOBEC3G from a human kidney cDNA library and confirmed that the protein acts as a potent inhibitor of HIV replication and is sensitive to the activity of Vif. We found that wild-type Vif inhibits packaging of APOBEC3G into virus particles in a dose-dependent manner. In contrast, biologically inactive variants carrying in-frame deletions in various regions of Vif or mutation of two highly conserved cysteine residues did not inhibit packaging of APOBEC3G. Interestingly, expression of APOBEC3G in the presence of wild-type Vif not only affected viral packaging but also reduced its intracellular expression level. This effect was not seen in the presence of biologically inactive Vif variants. Pulse-chase analyses did not reveal a significant difference in the stability of APOBEC3G in the presence or absence of Vif. However, in the presence of Vif, the rate of synthesis of APOBEC3G was slightly reduced. The reduction of intracellular APOBEC3G in the presence of Vif does not fully account for the Vif-induced reduction of virus-associated APOBEC3G, suggesting that Vif may function at several levels to prevent packaging of APOBEC3G into virus particles.
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Affiliation(s)
- Sandra Kao
- Laboratory of Molecular Microbiology, Viral Biochemistry Section, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, Maryland 20892-0460, USA
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19
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Gaddis NC, Chertova E, Sheehy AM, Henderson LE, Malim MH. Comprehensive investigation of the molecular defect in vif-deficient human immunodeficiency virus type 1 virions. J Virol 2003; 77:5810-20. [PMID: 12719574 PMCID: PMC154025 DOI: 10.1128/jvi.77.10.5810-5820.2003] [Citation(s) in RCA: 59] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023] Open
Abstract
Replication of human immunodeficiency virus type 1 (HIV-1) in primary blood lymphocytes, certain T-cell lines (nonpermissive cells), and most likely in vivo is highly dependent on the virally encoded Vif protein. Evidence suggests that Vif acts late in the viral life cycle during assembly, budding, and/or maturation to counteract the antiviral activity of the CEM15 protein and possibly other antiviral factors. Because HIV-1 virions produced in the absence of Vif are severely restricted at a postentry, preintegration step of infection, it is presumed that such virions differ from wild-type virions in some way. In the present study, we established a protocol for producing large quantities of vif-deficient HIV-1 (HIV-1/Delta vif) from an acute infection of nonpermissive T cells and performed a thorough examination of the defect in these virions. Aside from the expected lack of Vif, we observed no apparent abnormalities in the packaging, modification, processing, or function of proteins in Delta vif virions. In addition, we found no consistent defect in the ability of Delta vif virions to perform intravirion reverse transcription under a variety of assay conditions, suggesting that the reverse transcription complexes in these particles can behave normally under cell-free conditions. Consistent with this finding, neither the placement of the primer tRNA3Lys nor its ability to promote reverse transcription in an in vitro assay was affected by a lack of Vif. Based on the inability of this comprehensive analysis to uncover molecular defects in Delta vif virions, we speculate that such defects are likely to be subtle and/or rare.
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Affiliation(s)
- Nathan C Gaddis
- Department of Microbiology, University of Pennsylvania School of Medicine, Philadelphia, Pennsylvania 19104, USA
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20
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Ueno F, Shiota H, Miyaura M, Yoshida A, Sakurai A, Tatsuki J, Koyama AH, Akari H, Adachi A, Fujita M. Vpx and Vpr proteins of HIV-2 up-regulate the viral infectivity by a distinct mechanism in lymphocytic cells. Microbes Infect 2003; 5:387-95. [PMID: 12737994 DOI: 10.1016/s1286-4579(03)00042-x] [Citation(s) in RCA: 38] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
Mutants of human immunodeficiency virus type 2 (HIV-2) carrying a frame-shift mutation in vpx, vpr, and in both genes were monitored for their growth potentials in a newly established lymphocytic cell line, HSC-F. Worthy of note, the replication of a vpx single mutant, but not vpr, was severely impaired in these cells, and that of a vpx-vpr double mutant was more damaged. Defective replication sites of the vpx single and vpx-vpr double mutants were demonstrated to be mapped, respectively, to the nuclear import of viral genome, and to both, this process and the virus assembly/release stage. While the mutational effect of vpr was small, the replication efficiency in one cycle of the vpx mutant relative to that of wild-type virus was estimated to be 10%. The growth phenotypes of the vpx, vpr, and vpx-vpr mutant viruses in HSC-F cells were essentially repeated in primary human lymphocytes. In primary human macrophages, whereas the vpx and vpx-vpr mutants did not grow at all, the vpr mutant grew equally as well as the wild-type virus. These results strongly suggested that Vpx is critical for up-regulation of HIV-2 replication in natural target cells by enhancing the genome nuclear import, and that Vpr promotes HIV-2 replication somewhat, at least in lymphocytic cells, at a very late replication phase.
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Affiliation(s)
- Fumiko Ueno
- Department of Ophthalmology and Visual Neuroscience, The University of Tokushima School of Medicine, Tokushima 770-8503, Japan
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21
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Kao S, Akari H, Khan MA, Dettenhofer M, Yu XF, Strebel K. Human immunodeficiency virus type 1 Vif is efficiently packaged into virions during productive but not chronic infection. J Virol 2003; 77:1131-40. [PMID: 12502829 PMCID: PMC140813 DOI: 10.1128/jvi.77.2.1131-1140.2003] [Citation(s) in RCA: 51] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Packaging of the human immunodeficiency virus type 1 Vif protein into virus particles is mediated through an interaction with viral genomic RNA and results in the association of Vif with the nucleoprotein complex. Despite the specificity of this process, calculations of the amount of Vif packaged have produced vastly different results. Here, we compared the efficiency of packaging of Vif into virions derived from acutely and chronically infected H9 cells. We found that Vif was efficiently packaged into virions from acutely infected cells (60 to 100 copies per virion), while packaging into virions from chronically infected H9 cells was near the limit of detection (four to six copies of Vif per virion). Superinfection by an exogenous Vif-defective virus did not rescue packaging of endogenous Vif expressed in the chronically infected culture. In contrast, exogenous Vif expressed by superinfection of wild-type virus was readily packaged (30 to 40 copies per virion). Biochemical analyses suggest that the differences in the relative packaging efficiencies were not due to gross differences in the steady-state distribution of Vif in chronically or acutely infected cells but are likely due to differences in the relative rates of de novo synthesis of Vif. Despite its low packaging efficiency, endogenously expressed Vif was sufficient to direct the production of viruses with almost wild-type infectivity. The results from our study provide novel insights into the biochemical properties of Vif and offer an explanation for the reported differences regarding Vif packaging.
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Affiliation(s)
- Sandra Kao
- Laboratory of Molecular Microbiology, Viral Biochemistry Section, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, Maryland 20892-0460, USA
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22
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Fujita M, Sakurai A, Yoshida A, Miyaura M, Koyama AH, Sakai K, Adachi A. Amino acid residues 88 and 89 in the central hydrophilic region of human immunodeficiency virus type 1 Vif are critical for viral infectivity by enhancing the steady-state expression of Vif. J Virol 2003; 77:1626-32. [PMID: 12502880 PMCID: PMC140823 DOI: 10.1128/jvi.77.2.1626-1632.2003] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
A hydrophilic region consisting of strikingly clustered charged amino acids is present at the center of human immunodeficiency virus type 1 (HIV-1) Vif. In this study, the role for this central hydrophilic region (E(88)WRKKR(93)) in the virus replication in nonpermissive H9 cells was investigated by extensive deletion and substitution analysis. A total of 31 mutants were constructed. Deletion of the E(88) or W(89) residue alone abolished viral infectivity in H9 cells and impaired virus replication in primary macrophage cultures. Substitution analysis indicated that the hydrophilicity and charge of the central region are insignificant for the function of Vif. Of the 16 substitution mutants, 3 mutants with substitution of E(88) and W(89) with an A residue did not grow in H9 cells. Upon transfection, four mutants (i.e., two mutants with deletion of E(88) or W(89); a mutant with substitution of E(88) and W(89) with A; and a mutant with substitution of E(88), W(89), and R(90) with A) were found to express Vif at a very reduced level relative to that by the wild-type clone. These results have thus demonstrated that amino acid residues 88 and 89 of Vif are critical for the replication of HIV-1 in target cells by enhancing the steady-state expression of Vif. In addition, E(88) and W(89) residues were found to be extremely conserved among the Vif proteins of naturally occurring HIV-1 field isolates as well as those of laboratory HIV-1 strains.
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Affiliation(s)
- Mikako Fujita
- Department of Virology, The University of Tokushima Graduate School of Medicine, Japan
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23
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Fujita M, Matsumoto S, Sakurai A, Doi N, Miyaura M, Yoshida A, Adachi A. Apparent lack of trans-dominant negative effects of various vif mutants on the replication of HIV-1. Microbes Infect 2002; 4:1203-7. [PMID: 12467760 DOI: 10.1016/s1286-4579(02)01646-5] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
The vif gene of human immunodeficiency virus type 1 (HIV-1) is essential for virus growth in non-permissive cells such as H9. To elucidate the mechanism of action of the Vif protein, vif mutants, which show trans-dominant negative effects on the replication of HIV-1, would be useful tools. In this study, a new assay system to identify the mutants of this category was established. For this new system, various reporter clones carrying both mutant and authentic vif sequences were generated. By determining the growth ability of the viruses derived from the reporter constructs, the potential negative effect of the mutant vif sequence was readily and sensitively monitored. Ten vif mutant sequences tested were found not to exert the trans-dominant negative effect on the replication of HIV-1.
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Affiliation(s)
- Mikako Fujita
- Department of Virology, The University of Tokushima Graduate School of Medicine, Tokushima-shi, Tokushima 770-8503, Japan.
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24
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Khan MA, Akari H, Kao S, Aberham C, Davis D, Buckler-White A, Strebel K. Intravirion processing of the human immunodeficiency virus type 1 Vif protein by the viral protease may be correlated with Vif function. J Virol 2002; 76:9112-23. [PMID: 12186895 PMCID: PMC136454 DOI: 10.1128/jvi.76.18.9112-9123.2002] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The human immunodeficiency virus type 1 (HIV-1) Vif protein is specifically packaged into virus particles through an interaction with viral genomic RNA in which it associates with the viral nucleoprotein complex. We now demonstrate for the first time that virus-associated Vif is subject to proteolytic processing by the viral protease (Pr). Pr-dependent processing of Vif was observed both in vivo and in vitro. In vivo processing of Vif was cell type independent and evident by the appearance of a 7-kDa processing product, which was restricted to cell-free virus preparations. Processing of Vif required an active viral Pr and was sensitive to Pr inhibitors such as ritonavir. The processing site in Vif was characterized both in vivo and in vitro and mapped to Ala(150). Interestingly, the Vif processing site is located in a domain that is highly conserved among HIV-1, HIV-2, and simian immunodeficiency virus Vif isolates. Mutations at or near the processing site did not affect protein stability or packaging efficiency but had dramatic effects on Vif processing. In general, mutations that markedly increased or decreased the sensitivity of Vif to proteolytic processing severely impaired or completely abolished Vif function. In contrast, mutations at the same site that had little or no effect on processing efficiency also did not influence Vif function. None of the mutants affected the ability of the virus to replicate in permissive cell lines. Our data suggest that mutations in Vif that cause a profound change in the sensitivity to Pr-dependent processing also severely impaired Vif function, suggesting that intravirion processing of Vif is important for the production of infectious viruses.
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Affiliation(s)
- Mohammad A Khan
- Laboratory of Molecular Microbiology. Viral Biochemistry Section, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, Maryland 20892, USA
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25
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Goncalves J, Silva F, Freitas-Vieira A, Santa-Marta M, Malhó R, Yang X, Gabuzda D, Barbas C. Functional neutralization of HIV-1 Vif protein by intracellular immunization inhibits reverse transcription and viral replication. J Biol Chem 2002; 277:32036-45. [PMID: 12039955 DOI: 10.1074/jbc.m201906200] [Citation(s) in RCA: 61] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Human immunodeficiency virus type 1 (HIV-1)-encoded Vif protein is important for viral replication and infectivity. Vif is a cytoplasmic protein that acts during virus assembly by an unknown mechanism, enhancing viral infectivity. The action of Vif in producer cells is essential for the completion of proviral DNA synthesis following virus entry. Therefore, Vif is considered to be an important alternative therapeutic target for inhibition of viral infectivity at the level of viral assembly and reverse transcription. To gain insight into this process, we developed a Vif-specific single-chain antibody and expressed it intracellularly in the cytoplasm. This intrabody efficiently bound Vif protein and neutralized its infectivity-enhancing function. Intrabody-expressing cells were shown to be highly refractory to challenge with different strains of HIV-1 and HIV-1-infected cells. Inhibition of Vif by intrabody expression in the donor cell produced viral particles that do not complete reverse transcription in the recipient cell. The anti-Vif scFv was shown to be specific for Vif protein because its function was observed only in nonpermissive cells (H9, CEM, and U38). Moreover, transduction of peripheral blood mononuclear cells with an HIV-derived retroviral vector expressing Vif intrabody was shown to confer resistance to laboratory-adapted and primary HIV strains. This study provides biochemical evidence for the role of Vif in the HIV-1 lifecycle and validates Vif as a target for the control of HIV-1 infection.
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Affiliation(s)
- Joao Goncalves
- URIA-Centro de Patogénese Molecular, Faculdade de Farmácia, University of Lisbon, 1649-019 Portugal.
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26
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Serhan F, Jourdan N, Saleun S, Moullier P, Duisit G. Characterization of producer cell-dependent restriction of murine leukemia virus replication. J Virol 2002; 76:6609-17. [PMID: 12050374 PMCID: PMC136263 DOI: 10.1128/jvi.76.13.6609-6617.2002] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2002] [Accepted: 03/21/2002] [Indexed: 11/20/2022] Open
Abstract
We previously reported that the human bronchocarcinoma cell line A549 produces poorly infectious gibbon ape leukemia virus-pseudotyped Moloney murine leukemia virus (MLV). In contrast, similar amounts of virions recovered from human fibrosarcoma HT1080 cells result in 10-fold-higher transduction rates (G. Duisit, A. Salvetti, P. Moullier, and F. Cosset, Hum. Gene Ther. 10:189-200, 1999). We have now extended this initial observation to other type-C envelope (Env) pseudotypes and analyzed the mechanism involved. Structural and morphological analysis showed that viral particles recovered from A549 (A549-MLV) and HT1080 (HT1080-MLV) cells were normal and indistinguishable from each other. They expressed equivalent levels of mature Env proteins and bound similarly to the target cells. Furthermore, incoming particles reached the cytosol and directed the synthesis of linear viral DNA equally efficiently. However, almost no detectable circular DNAs could be detected in A549-MLV-infected cells, indicating that the block of infection resulted from defective nuclear translocation of the preintegration complex. Interestingly, pseudotyping of A549-MLV with vesicular stomatitis virus glycoprotein G restored the amount of circular DNA forms as well as the transduction rates to HT1080-MLV levels, suggesting that the postentry blockage could be overcome by endocytic delivery of the core particles downstream of the restriction point. Thus, in contrast to the previously described target cell-dependent Fv-1 (or Fv1-like) restriction in mammalian cells (P. Pryciak and H. E. Varmus, J. Virol. 66:5959-5966, 1992; G. Towers, M. Bock, S. Martin, Y. Takeuchi, J. P. Stoye, and O. Danos, Proc. Natl. Acad. Sci. USA 97:12295-12299, 2000), we report here a new restriction of MLV replication that relies only on the producer cell type.
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Affiliation(s)
- Fatima Serhan
- Laboratoire de Thérapie Génique, INSERM ERM 0-105, CHU Hotel Dieu, 30 boulevard Jean Monnet, 44035 Nantes Cedex 01, France
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27
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Fujita M, Sakurai A, Doi N, Miyaura M, Yoshida A, Sakai K, Adachi A. Analysis of the cell-dependent replication potentials of human immunodeficiency virus type 1 vif mutants. Microbes Infect 2001; 3:1093-9. [PMID: 11709289 DOI: 10.1016/s1286-4579(01)01469-1] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Eleven in-frame vif gene mutants of HIV type 1 produced in non-permissive cells were examined for their replication potentials in various CD4-positive and -negative cell lines. Virus replication for each mutant was monitored by using several single- and multiple-cycle infectivity assays. Except for a mutant with wild-type phenotype, most mutants were severely defective for replication in all the cell lines as expected from the producer cell-dependent functioning of Vif so far reported. In contrast, two mutants, which have mutations in the hydrophilic or effector regions of Vif were found to have target cell-dependent replication potentials. These results demonstrate the presence of a novel category of the vif mutants important for elucidation of the Vif function.
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Affiliation(s)
- M Fujita
- Department of Virology, The University of Tokushima School of Medicine, Tokushima-shi, 770-8503, Tokushima, Japan.
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28
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McKnight A, Griffiths DJ, Dittmar M, Clapham P, Thomas E. Characterization of a late entry event in the replication cycle of human immunodeficiency virus type 2. J Virol 2001; 75:6914-22. [PMID: 11435571 PMCID: PMC114419 DOI: 10.1128/jvi.75.15.6914-6922.2001] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/14/2000] [Accepted: 05/08/2001] [Indexed: 12/13/2022] Open
Abstract
Certain human cell lines and primary macrophage cultures are restricted to infection by some primary isolates of human immunodeficiency virus type 2 (HIV-2), although early steps of the viral life cycle such as fusion at the plasma membrane and reverse transcription are fully supported. The late postintegration events, transcription, translation, assembly, budding, and maturation into infectious virions are functional in restrictive cells. Apart from primary macrophages, the restrictive cell types are actively dividing, and nuclear import of preintegration complexes (PICs) is not required for infection. We therefore postulate that the PICs are trapped in a cellular compartment, preventing subsequent steps in the replication cycle that lead to integration of the provirus. To test this we showed that HIV-2 particles pseudotyped with vesicular stomatitis virus envelope G protein, which delivers HIV into an endocytic compartment, could overcome the block to infection. We suggest that delivery of the viral core into an appropriate cellular compartment is a critical step during the entry process of HIV.
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Affiliation(s)
- McKnight A
- Wohl Virion Centre, Windeyer Institute of Medical Sciences, University College London, London W1T 4JF, United Kingdom.
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29
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Khan MA, Aberham C, Kao S, Akari H, Gorelick R, Bour S, Strebel K. Human immunodeficiency virus type 1 Vif protein is packaged into the nucleoprotein complex through an interaction with viral genomic RNA. J Virol 2001; 75:7252-65. [PMID: 11461998 PMCID: PMC114961 DOI: 10.1128/jvi.75.16.7252-7265.2001] [Citation(s) in RCA: 108] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The human immunodeficiency virus type 1 (HIV-1) Vif protein plays a critical role in the production of infectious virions. Previous studies have demonstrated the presence of small amounts of Vif in virus particles. However, Vif packaging was assumed to be nonspecific, and its functional significance has been questioned. We now report that packaging of Vif is dependent on the packaging of viral genomic RNA in both permissive and restrictive HIV-1 target cells. Mutations in the nucleocapsid zinc finger domains that abrogate packaging of viral genomic RNA abolished packaging of Vif. Additionally, an RNA packaging-defective virus exhibited significantly reduced packaging of Vif. Finally, deletion of a putative RNA-interacting domain in Vif abolished packaging of Vif into virions. Virion-associated Vif was resistant to detergent extraction and copurified with components of the viral nucleoprotein complex and functional reverse transcription complexes. Thus, Vif is specifically packaged into virions as a component of the viral nucleoprotein complex. Our data suggest that the specific association of Vif with the viral nucleoprotein complex might be functionally significant and could be a critical requirement for infectivity of viruses produced from restrictive host cells.
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Affiliation(s)
- M A Khan
- Laboratory of Molecular Microbiology, Viral Biochemistry Section, National Institute of Allergy and Infectious Diseases, NIH, Bethesda, Maryland 20892-0460, USA
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Henzler T, Harmache A, Herrmann H, Spring H, Suzan M, Audoly G, Panek T, Bosch V. Fully functional, naturally occurring and C-terminally truncated variant human immunodeficiency virus (HIV) Vif does not bind to HIV Gag but influences intermediate filament structure. J Gen Virol 2001; 82:561-573. [PMID: 11172097 DOI: 10.1099/0022-1317-82-3-561] [Citation(s) in RCA: 20] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
A variant human immunodeficiency virus type 1 (HIV-1) vif gene, vifA45-2, which encodes a protein lacking 19 amino acids at the C terminus but which is fully functional in supporting HIV replication in non-permissive cells has been described previously. By employing newly generated anti-VifA45 serum, further properties of VifA45 and its full-length counterpart, VifA45open, in comparison to Vif from HIV strain BH10 are reported in permissive HeLa and COS-7 cells. The results obtained using confocal microscopic localization studies and in vitro binding assays do not support a requirement for the direct interaction of HIV Gag with Vif. Furthermore and in contrast to previous conclusions, detergent solubility analyses do not demonstrate a role for the C terminus of Vif in mediating localization to the fraction containing cellular membrane proteins. Localization of Vif from HIV strain BH10 to perinuclear aggregates in a small fraction (about 10%) of transfected HeLa cells has been previously reported. The intermediate filament protein vimentin colocalizes to these structures. In contrast, VifA45 and VifA45open form perinuclear aggregates in nearly all transfected HeLa cells; vimentin as well as the cytoskeletal-bridging protein plectin, but not the microtubular protein tubulin, become relocalized to these structures. Interestingly, in COS-7 cells, all of the functional Vif proteins tested (Vif from strain BH10, VifA45 and VifA45open) predominantly localize in the cytoplasm but still induce dramatic aggregation of vimentin and plectin, i.e. in these cells the respective Vif proteins are influencing intermediate filament structure in the absence of colocalization.
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Affiliation(s)
- Tanja Henzler
- Forschungsschwerpunkt Angewandte Tumorvirologie, F02001, and Forschungsschwerpunkt Krebsentstehung und Differenzierung, A01002, Deutsches Krebsforschungszentrum, Im Neuenheimer Feld 242, D-69120 Heidelberg, Germany
| | - Abdallah Harmache
- Forschungsschwerpunkt Angewandte Tumorvirologie, F02001, and Forschungsschwerpunkt Krebsentstehung und Differenzierung, A01002, Deutsches Krebsforschungszentrum, Im Neuenheimer Feld 242, D-69120 Heidelberg, Germany
| | - Harald Herrmann
- Forschungsschwerpunkt Angewandte Tumorvirologie, F02001, and Forschungsschwerpunkt Krebsentstehung und Differenzierung, A01002, Deutsches Krebsforschungszentrum, Im Neuenheimer Feld 242, D-69120 Heidelberg, Germany
| | - Herbert Spring
- Forschungsschwerpunkt Angewandte Tumorvirologie, F02001, and Forschungsschwerpunkt Krebsentstehung und Differenzierung, A01002, Deutsches Krebsforschungszentrum, Im Neuenheimer Feld 242, D-69120 Heidelberg, Germany
| | - Marie Suzan
- Pathogénie des Infections à Lentivirus, INSERM U372, BP178, 13276 Marseille, France3
| | - Gilles Audoly
- Pathogénie des Infections à Lentivirus, INSERM U372, BP178, 13276 Marseille, France3
| | - Therese Panek
- Forschungsschwerpunkt Angewandte Tumorvirologie, F02001, and Forschungsschwerpunkt Krebsentstehung und Differenzierung, A01002, Deutsches Krebsforschungszentrum, Im Neuenheimer Feld 242, D-69120 Heidelberg, Germany
| | - Valerie Bosch
- Forschungsschwerpunkt Angewandte Tumorvirologie, F02001, and Forschungsschwerpunkt Krebsentstehung und Differenzierung, A01002, Deutsches Krebsforschungszentrum, Im Neuenheimer Feld 242, D-69120 Heidelberg, Germany
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Koh K, Miyaura M, Yoshida A, Sakurai A, Fujita M, Adachi A. Cell-dependent gag mutants of HIV-1 are crucially defective at the stage of uncoating/reverse transcription in non-permissive cells. Microbes Infect 2000; 2:1419-23. [PMID: 11099927 DOI: 10.1016/s1286-4579(00)01295-8] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
Abstract
We have previously shown that some of the human immunodeficiency virus type 1 (HIV-1) gag matrix (MA), capsid (CA), and nucleocapsid (NC) mutants display host-cell-dependent replication potential, and that they are defective at the early phase of the virus replication cycle in non-permissive cells. To determine the defective replication stage of the cell-dependent mutants precisely, the processes of virus entry into cells and virus DNA synthesis were monitored by the highly sensitive enzyme-linked immunosorbent assay and polymerase chain reaction amplification analysis. The results obtained indicated that all the cell-dependent MA, CA and NC mutants are defective at the stage of uncoating/reverse transcription, and that a cellular factor(s) is involved in this process.
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Affiliation(s)
- K Koh
- Department of Virology, School of Medicine, The University of Tokushima, 770-8503, Tokushima, Japan
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Akari H, Yoshida A, Fukumori T, Adachi A. Host cell-dependent replication of HIV-1 mutants with deletions in gp41 cytoplasmic tail region is independent of the function of Vif. Microbes Infect 2000; 2:1019-23. [PMID: 11032465 DOI: 10.1016/s1286-4579(00)01256-9] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
Affiliation(s)
- H Akari
- Department of Virology, The University of Tokushima School of Medicine, Tokushima, Japan
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Fukumori T, Akari H, Yoshida A, Fujita M, Koyama AH, Kagawa S, Adachi A. Regulation of cell cycle and apoptosis by human immunodeficiency virus type 1 Vpr. Microbes Infect 2000; 2:1011-7. [PMID: 10967282 DOI: 10.1016/s1286-4579(00)01255-7] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Biological effects of HIV-1 Vpr on CD4(+) cells were studied by an infection system. High-titered HIV-1 stocks pseudotyped with vesicular stomatitis virus G protein were prepared and used to inoculate into CD4(+ )T cells at high multiplicity of infection. Both cell- and virion-associated Vpr were demonstrated to arrest the cell cycle at the G2/M phase, and to induce cell apoptosis. Of note, morphologically apoptotic cells were shown to be arrested at the G2/M stage. No appreciable effect of Vpr on the anti-Fas antibody-mediated apoptosis was observed in this system.
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Affiliation(s)
- T Fukumori
- Department of Virology, The University of Tokushima School of Medicine, 770-8503, Tokushima, Japan
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Akari H, Fukumori T, Adachi A. Cell-dependent requirement of human immunodeficiency virus type 1 gp41 cytoplasmic tail for Env incorporation into virions. J Virol 2000; 74:4891-3. [PMID: 10775630 PMCID: PMC112014 DOI: 10.1128/jvi.74.10.4891-4893.2000] [Citation(s) in RCA: 84] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Growth kinetics in lymphocytic H9 and M8166 cells of two mutants of human immunodeficiency virus type 1 (HIV-1) with deleted gp41 cytoplasmic tails were examined. While the mutant viruses designated CTdel-44 and CTdel-144 were able to grow in M8166 cells, they were unable to grow in H9 cells. Transfection and single-round infectivity assays demonstrated that they are defective in the early phase of viral replication in H9 cells. Analysis of the mutant virions revealed drastically reduced incorporation of Env gp120 (compared with the incorporation of wild-type virions) in H9 cells but normal incorporation in M8166 cells. These results indicate that the HIV-1 cytoplasmic tail of gp41 determines virus infectivity in a cell-dependent manner by affecting incorporation of Env into virions and suggest the involvement of a host cell factor(s) in the Env incorporation.
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Affiliation(s)
- H Akari
- Department of Virology, The University of Tokushima School of Medicine, Tokushima 770-8503, Japan
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Akari H, Arold S, Fukumori T, Okazaki T, Strebel K, Adachi A. Nef-induced major histocompatibility complex class I down-regulation is functionally dissociated from its virion incorporation, enhancement of viral infectivity, and CD4 down-regulation. J Virol 2000; 74:2907-12. [PMID: 10684310 PMCID: PMC111784 DOI: 10.1128/jvi.74.6.2907-2912.2000] [Citation(s) in RCA: 94] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The N-terminal alpha-helix domain of the human immunodeficiency virus type 1 (HIV-1) Nef protein plays important roles in enhancement of viral infectivity, virion incorporation of Nef, and the down-regulation of major histocompatibility complex class I (MHC-I) expression on cell surfaces. In this study, we demonstrated that Met 20 in the alpha-helix domain was indispensable for the ability of Nef to modulate MHC-I expression but not for other events. We also showed that Met 20 was unnecessary for the down-regulation of CD4. These findings indicate that the region governing MHC-I down-regulation is proximate in the alpha-helix domain but is dissociated functionally from that determining enhancement of viral infectivity, virion incorporation of Nef, and CD4 down-regulation.
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Affiliation(s)
- H Akari
- Department of Virology, The University of Tokushima School of Medicine, Tokushima, Tokushima 770-8503, Japan.
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