scholarly journals The Leader of Human Immunodeficiency Virus Type 1 Genomic RNA Harbors an Internal Ribosome Entry Segment That Is Active during the G2/M Phase of the Cell Cycle

2003 ◽  
Vol 77 (7) ◽  
pp. 3939-3949 ◽  
Author(s):  
Ann Brasey ◽  
Marcelo Lopez-Lastra ◽  
Theophile Ohlmann ◽  
Nancy Beerens ◽  
Ben Berkhout ◽  
...  
Keyword(s):  
Cell Cycle ◽  
Human Immunodeficiency Virus ◽  
Protein Synthesis ◽  
Human Immunodeficiency Virus Type ◽  
Genomic Rna ◽  
M Cell ◽  
Internal Ribosome Entry ◽  
Immunodeficiency Virus ◽  
Hiv 1

ABSTRACT The 5′ leader of the human immunodeficiency virus type 1 (HIV-1) genomic RNA contains highly structured domains involved in key steps of the viral life cycle. These RNA domains inhibit cap-dependent protein synthesis. Here we report that the HIV-1 5′ leader harbors an internal ribosome entry site (IRES) capable of driving protein synthesis during the G2/M cell cycle phase in which cap-dependent initiation is inhibited. The HIV-1 IRES was delineated with bicistronic mRNAs in in vitro and ex vivo assays. The HIV-1 leader IRES spans nucleotides 104 to 336 and partially overlaps the major determinants of genomic RNA packaging. These data strongly suggest that, as for HIV-1 transcription, IRES-mediated translation initiation could play an important role in virus replication during virus-induced G2/M cell cycle arrest.

scholarly journals Human Immunodeficiency Virus Type 1 Nucleocapsid Protein Nuclear Localization Mediates Early Viral mRNA Expression

2002 ◽  
Vol 76 (20) ◽  
pp. 10444-10454 ◽  
Author(s):  
Jielin Zhang ◽  
Clyde S. Crumpacker
Keyword(s):  
Human Immunodeficiency Virus ◽  
Mrna Expression ◽  
Human Immunodeficiency Virus Type ◽  
Virus Type ◽  
Nucleocapsid Protein ◽  
Viral Mrna ◽  
Genomic Rna ◽  
Immunodeficiency Virus ◽  
Hiv 1

ABSTRACT An important aspect of the pathophysiology of human immunodeficiency virus type 1 (HIV-1) infection is the ability of the virus to replicate in the host vigorously without a latent phase and to kill cells with a dynamic turnover of 1.8 × 109 cells/day and 10.3 × 109 virions/24 h. The transcription of HIV-1 RNA in acute infection occurs at two stages; the transcription of viral spliced mRNA occurs early, and the transcription of viral genomic RNA occurs later. The HIV-1 Tat protein is translated from the early spliced mRNA and is critical for HIV-1 genomic RNA expression. The cellular transcription factors are important for HIV-1 early spliced mRNA expression. In this study we show that virion nucleocapsid protein (NC) has a role in expression of HIV-1 early spliced mRNA. The HIV-1 NC migrates from the cytoplasm to the nucleus and accumulates in the nucleus at 18 h postinfection. Mutations on HIV-1 NC zinc fingers change the pattern of early viral spliced mRNA expression and result in a delayed expression of early viral mRNA in HIV-infected cells. This delayed HIV-1 early spliced mRNA expression occurs after proviral DNA has been integrated into the cellular genome, as shown by a quantitative integration assay. These results show that virion NC plays an important role in inducing HIV-1 early mRNA expression and contributes to the rapid viral replication that occurs during HIV-1 infection.

scholarly journals A Human Nuclear Shuttling Protein That Interacts with Human Immunodeficiency Virus Type 1 Matrix Is Packaged into Virions

2000 ◽  
Vol 74 (24) ◽  
pp. 11811-11824 ◽  
Author(s):  
Kalpana Gupta ◽  
David Ott ◽  
Thomas J. Hope ◽  
Robert F. Siliciano ◽  
Jef D. Boeke
Keyword(s):  
Human Immunodeficiency Virus ◽  
Human Immunodeficiency Virus Type ◽  
Virus Type ◽  
Nuclear Import ◽  
Productive Infection ◽  
Genomic Rna ◽  
Virion Production ◽  
Immunodeficiency Virus ◽  
Hiv 1

ABSTRACT Active nuclear import of the human immunodeficiency virus type 1 (HIV-1) preintegration complex (PIC) is essential for the productive infection of nondividing cells. Nuclear import of the PIC is mediated by the HIV-1 matrix protein, which also plays several critical roles during viral entry and possibly during virion production facilitating the export of Pr55Gag and genomic RNA. Using a yeast two-hybrid screen, we identified a novel human virion-associated matrix-interacting protein (VAN) that is highly conserved in vertebrates and expressed in most human tissues. Its expression is upregulated upon activation of CD4+ T cells. VAN is efficiently incorporated into HIV-1 virions and, like matrix, shuttles between the nucleus and cytoplasm. Furthermore, overexpression of VAN significantly inhibits HIV-1 replication in tissue culture. We propose that VAN regulates matrix nuclear localization and, by extension, both nuclear import of the PIC and export of Pr55Gag and viral genomic RNA during virion production. Our data suggest that this regulatory mechanism reflects a more global process for regulation of nucleocytoplasmic transport.

scholarly journals Human Immunodeficiency Virus Type 1 (HIV-1) Vpr Enhances Expression from Unintegrated HIV-1 DNA

2003 ◽  
Vol 77 (7) ◽  
pp. 3962-3972 ◽  
Author(s):  
Betty Poon ◽  
Irvin S. Y. Chen
Keyword(s):  
Cell Cycle ◽  
Human Immunodeficiency Virus ◽  
Cell Cycle Arrest ◽  
Human Immunodeficiency Virus Type ◽  
Virus Type ◽  
Viral Dna ◽  
Cycle Arrest ◽  
Immunodeficiency Virus ◽  
Hiv 1

ABSTRACT Retroviral DNA synthesized prior to integration, termed unintegrated viral DNA, is classically believed to be transcriptionally inert and to serve only as a precursor to the transcriptionally active integrated proviral DNA form. However, it has recently been found to be expressed under some circumstances during human immunodeficiency virus type 1 (HIV-1) replication and may play a significant role in HIV-1 pathogenesis. HIV-1 Vpr is a virion-associated accessory protein that is critical for HIV-1 replication in nondividing cells and induces cell cycle arrest and apoptosis. We find that Vpr, either expressed de novo or released from virions following viral entry, is essential for unintegrated viral DNA expression. HIV-1 mutants defective for integration in either the integrase catalytic domain or the cis-acting att sites can express unintegrated viral DNA at levels similar to that of wild-type HIV-1, but only in the presence of Vpr. In the absence of Vpr, the expression of unintegrated viral DNA decreases 10- to 20-fold. Vpr does not affect the efficiency of integration from integrase-defective HIV-1. Vpr-mediated enhancement of expression from integrase-defective HIV-1 requires that the viral DNA be generated in cells through infection and is mediated via a template that declines over time. Vpr activation of expression does not require exclusive nuclear localization of Vpr nor does it correlate with Vpr-mediated cell cycle arrest. These results attribute a new function to HIV-1 Vpr and implicate Vpr as a critical component in expression from unintegrated HIV-1 DNA.

scholarly journals Human Immunodeficiency Virus Type 1 Vpr-Binding Protein VprBP, a WD40 Protein Associated with the DDB1-CUL4 E3 Ubiquitin Ligase, Is Essential for DNA Replication and Embryonic Development

2008 ◽  
Vol 28 (18) ◽  
pp. 5621-5633 ◽  
Author(s):  
Chad M. McCall ◽  
Paula L. Miliani de Marval ◽  
Paul D. Chastain ◽  
Sarah C. Jackson ◽  
Yizhou J. He ◽  
...  
Keyword(s):  
Cell Cycle ◽  
Human Immunodeficiency Virus ◽  
Dna Replication ◽  
Human Immunodeficiency Virus Type ◽  
Virus Type ◽  
Binding Protein ◽  
S Phase ◽  
Immunodeficiency Virus ◽  
Hiv 1

ABSTRACT Damaged DNA binding protein 1, DDB1, bridges an estimated 90 or more WD40 repeats (DDB1-binding WD40, or DWD proteins) to the CUL4-ROC1 catalytic core to constitute a potentially large number of E3 ligase complexes. Among these DWD proteins is the human immunodeficiency virus type 1 (HIV-1) Vpr-binding protein VprBP, whose cellular function has yet to be characterized but has recently been found to mediate Vpr-induced G2 cell cycle arrest. We demonstrate here that VprBP binds stoichiometrically with DDB1 through its WD40 domain and through DDB1 to CUL4A, subunits of the COP9/signalsome, and DDA1. The steady-state level of VprBP remains constant during interphase and decreases during mitosis. VprBP binds to chromatin in a DDB1-independent and cell cycle-dependent manner, increasing from early S through G2 before decreasing to undetectable levels in mitotic and G1 cells. Silencing VprBP reduced the rate of DNA replication, blocked cells from progressing through the S phase, and inhibited proliferation. VprBP ablation in mice results in early embryonic lethality. Conditional deletion of the VprBP gene in mouse embryonic fibroblasts results in severely defective progression through S phase and subsequent apoptosis. Our studies identify a previously unknown function of VprBP in S-phase progression and suggest the possibility that HIV-1 Vpr may divert an ongoing chromosomal replication activity to facilitate viral replication.

Regulation of human immunodeficiency virus type 1 (HIV-1) mRNA translation

2017 ◽  
Vol 45 (2) ◽  
pp. 353-364 ◽  
Author(s):  
Laura Hidalgo ◽  
Chad M. Swanson
Keyword(s):  
Human Immunodeficiency Virus ◽  
Human Immunodeficiency Virus Type ◽  
Virus Type ◽  
Mrna Translation ◽  
Internal Ribosome Entry ◽  
Immunodeficiency Virus ◽  
Regulate Protein ◽  
Hiv 1

Human immunodeficiency virus type 1 (HIV-1) mRNA translation is a complex process that uses the host translation machinery to synthesise viral proteins. Several mechanisms for HIV-1 mRNA translation initiation have been proposed including (1) cap-dependent, eIF4E-dependent, (2) cap-dependent, cap-binding complex-dependent, (3) internal ribosome entry sites, and (4) ribosome shunting. While these mechanisms promote HIV-1 mRNA translation in the context of in vitro systems and subgenomic constructs, there are substantial knowledge gaps in understanding how they regulate viral protein production in the context of full-length virus infection. In this review, we will summarise the different translation mechanisms used by HIV-1 mRNAs and the challenges in understanding how they regulate protein synthesis during viral infection.

scholarly journals Elimination of Protease Activity Restores Efficient Virion Production to a Human Immunodeficiency Virus Type 1 Nucleocapsid Deletion Mutant

2003 ◽  
Vol 77 (10) ◽  
pp. 5547-5556 ◽  
Author(s):  
David E. Ott ◽  
Lori V. Coren ◽  
Elena N. Chertova ◽  
Tracy D. Gagliardi ◽  
Kunio Nagashima ◽  
...  
Keyword(s):  
Human Immunodeficiency Virus ◽  
Human Immunodeficiency Virus Type ◽  
Virus Type ◽  
Protease Activity ◽  
Genomic Rna ◽  
Wild Type ◽  
Virion Production ◽  
Immunodeficiency Virus ◽  
Hiv 1

ABSTRACT The nucleocapsid (NC) region of human immunodeficiency virus type 1 (HIV-1) Gag is required for specific genomic RNA packaging. To determine if NC is absolutely required for virion formation, we deleted all but seven amino acids from NC in a full-length NL4-3 proviral clone. This construct, DelNC, produced approximately four- to sixfold fewer virions than did the wild type, and these virions were noninfectious (less than 10−6 relative to the wild type) and severely genomic RNA deficient. Immunoblot and high-pressure liquid chromatography analyses showed that all of the mature Gag proteins except NC were present in the mutant virion preparations, although there was a modest decrease in Gag processing. DelNC virions had lower densities and were more heterogeneous than wild-type particles, consistent with a defect in the interaction assembly or I domain. Electron microscopy showed that the DelNC virions displayed a variety of aberrant morphological forms. Inactivating the protease activity of DelNC by mutation or protease inhibitor treatment restored virion production to wild-type levels. DelNC-protease mutants formed immature-appearing particles that were as dense as wild-type virions without incorporating genomic RNA. Therefore, protease activity combined with the absence of NC causes the defect in DelNC virion production, suggesting that premature processing of Gag during assembly causes this effect. These results show that HIV-1 can form particles efficiently without NC.

scholarly journals Human Cellular Nucleic Acid-Binding Protein Zn2+ Fingers Support Replication of Human Immunodeficiency Virus Type 1 When They Are Substituted in the Nucleocapsid Protein

2003 ◽  
Vol 77 (15) ◽  
pp. 8524-8531 ◽  
Author(s):  
Connor F. McGrath ◽  
James S. Buckman ◽  
Tracy D. Gagliardi ◽  
William J. Bosche ◽  
Lori V. Coren ◽  
...  
Keyword(s):  
Human Immunodeficiency Virus ◽  
Nucleic Acid ◽  
Human Immunodeficiency Virus Type ◽  
Virus Type ◽  
Structural Characteristics ◽  
Nucleic Acid Binding ◽  
Genomic Rna ◽  
Immunodeficiency Virus ◽  
Hiv 1

ABSTRACT A family of cellular nucleic acid binding proteins (CNBPs) contains seven Zn2+ fingers that have many of the structural characteristics found in retroviral nucleocapsid (NC) Zn2+ fingers. The sequence of the NH2-terminal NC Zn2+ finger of the pNL4-3 clone of human immunodeficiency virus type 1 (HIV-1) was replaced individually with sequences from each of the seven fingers from human CNBP. Six of the mutants were normal with respect to protein composition and processing, full-length genomic RNA content, and infectivity. One of the mutants, containing the fifth CNBP Zn2+ finger (CNBP-5) packaged reduced levels of genomic RNA and was defective in infectivity. There appear to be defects in reverse transcription in the CNBP-5 infections. Models of Zn2+ fingers were constructed by using computational methods based on available structural data, and atom-atom interactions were determined by the hydropathic orthogonal dynamic analysis of the protein method. Defects in the CNBP-5 mutant could possibly be explained, in part, by restrictions of a set of required atom-atom interactions in the CNBP-5 Zn2+ finger compared to mutant and wild-type Zn2+ fingers in NC that support replication. The present study shows that six of seven of the Zn2+ fingers from the CNBP protein can be used as substitutes for the Zn2+ finger in the NH2-terminal position of HIV-1 NC. This has obvious implications in antiviral therapeutics and DNA vaccines employing NC Zn2+ finger mutants.

scholarly journals The Double-Stranded RNA-Binding Protein Staufen Is Incorporated in Human Immunodeficiency Virus Type 1: Evidence for a Role in Genomic RNA Encapsidation

2000 ◽  
Vol 74 (12) ◽  
pp. 5441-5451 ◽  
Author(s):  
Andrew J. Mouland ◽  
Johanne Mercier ◽  
Ming Luo ◽  
Luc Bernier ◽  
Luc DesGroseillers ◽  
...  
Keyword(s):  
Human Immunodeficiency Virus ◽  
Human Immunodeficiency Virus Type ◽  
Virus Type ◽  
Binding Protein ◽  
Genomic Rna ◽  
Double Stranded Rna ◽  
Dsrna Binding ◽  
Immunodeficiency Virus ◽  
Hiv 1

ABSTRACT Human Staufen (hStau), a double-stranded RNA (dsRNA)-binding protein that is involved in mRNA transport, is incorporated in human immunodeficiency virus type 1 (HIV-1) and in other retroviruses, including HIV-2 and Moloney murine leukemia virus. Sucrose and Optiprep gradient analyses reveal cosedimentation of hStau with purified HIV-1, while subtilisin assays demonstrate that it is internalized. hStau incorporation in HIV-1 is selective, is dependent on an intact functional dsRNA-binding domain, and quantitatively correlates with levels of encapsidated HIV-1 genomic RNA. By coimmunoprecipitation and reverse transcription-PCR analyses, we demonstrate that hStau is associated with HIV-1 genomic RNA in HIV-1-expressing cells and purified virus. Overexpression of hStau enhances virion incorporation levels, and a corresponding, threefold increase in HIV-1 genomic RNA encapsidation levels. This coordinated increase in hStau and genomic RNA packaging had a significant negative effect on viral infectivity. This study is the first to describe hStau within HIV-1 particles and provides evidence that hStau binds HIV-1 genomic RNA, indicating that it may be implicated in retroviral genome selection and packaging into assembling virions.

scholarly journals Induction of Rapid and Extensive β-Chemokine Synthesis in Macrophages by Human Immunodeficiency Virus Type 1 and gp120, Independently of Their Coreceptor Phenotype

2001 ◽  
Vol 75 (22) ◽  
pp. 10738-10745 ◽  
Author(s):  
Wonkyu Choe ◽  
David J. Volsky ◽  
Mary Jane Potash
Keyword(s):  
Human Immunodeficiency Virus ◽  
Protein Synthesis ◽  
Human Immunodeficiency Virus Type ◽  
Virus Type ◽  
Productive Infection ◽  
Target Cells ◽  
Chemokine Production ◽  
Immunodeficiency Virus ◽  
Hiv 1

ABSTRACT Human immunodeficiency virus type 1 (HIV-1) interacts with its target cells through CD4 and a coreceptor, generally CCR5 or CXCR4. Macrophages display CD4, CCR5, and CXCR4 that are competent for binding and entry of virus. Virus binding also induces several responses by lymphocytes and macrophages that can be dissociated from productive infection. We investigated the responses of macrophages to exposure to a series of HIV-1 species, R5 species that productively infect and X4 species that do not infect macrophages. We chose to monitor production of several physiologically relevant factors within hours of treatment to resolve virally induced effects that may be unlinked to HIV-1 production. Our novel findings indicate that independently of their coreceptor phenotype and independently of virus replication, exposure to certain R5 and X4 HIV-1 species induced secretion of high levels of macrophage inflammatory protein 1α (MIP-1α), MIP-1β, RANTES, and tumor necrosis factor alpha. However two of the six R5 species tested, despite efficient infection, were unable to induce rapid chemokine production. The acute effects of virus on macrophages could be mimicked by exposure to purified R5 or the X4 HIV-1 envelope glycoprotein gp120. Depletion of intracellular Ca2+ or inhibition of protein synthesis blocked the chemokine induction, implicating Ca2+-mediated signal transduction and new protein synthesis in the response. The group of viruses able to induce this chemokine response was not consistent with coreceptor usage. We conclude that human macrophages respond rapidly to R5 and X4 envelope binding by production of high levels of physiologically active proteins that are implicated in HIV-1 pathogenesis.

scholarly journals Association of Human Immunodeficiency Virus Type 1 Vif with RNA and Its Role in Reverse Transcription

2000 ◽  
Vol 74 (19) ◽  
pp. 8938-8945 ◽  
Author(s):  
Markus Dettenhofer ◽  
Shan Cen ◽  
Bradley A. Carlson ◽  
Lawrence Kleiman ◽  
Xiao-Fang Yu
Keyword(s):  
Human Immunodeficiency Virus ◽  
Reverse Transcriptase ◽  
Human Immunodeficiency Virus Type ◽  
Virus Type ◽  
Reverse Transcription ◽  
Genomic Rna ◽  
Immunodeficiency Virus ◽  
Viral Genomic Rna ◽  
Hiv 1

ABSTRACT The vif gene of human immunodeficiency virus type 1 (HIV-1) is essential for viral replication, although the functional target of Vif remains elusive. HIV-1 vif mutant virions derived from nonpermissive H9 cells displayed no significant differences in the amount, ratio, or integrity of their protein composition relative to an isogenic wild-type virion. The amounts of the virion-associated viral genomic RNA and tRNA3 Lyswere additionally present at normal levels in vif mutant virions. We demonstrate that Vif associates with RNA in vitro as well as with viral genomic RNA in virus-infected cells. A functionally conserved lentivirus Vif motif was found in the double-stranded RNA binding domain of Xenopus laevis, Xlrbpa. The natural intravirion reverse transcriptase products were markedly reduced invif mutant virions. Moreover, purified vifmutant genomic RNA-primer tRNA complexes displayed severe defects in the initiation of reverse transcription with recombinant reverse transcriptase. These data point to a novel role for Vif in the regulation of efficient reverse transcription through modulation of the virion nucleic acid components.

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