scholarly journals Genome-Wide Analysis of Chromosomal Features Repressing Human Immunodeficiency Virus Transcription

2005 ◽  
Vol 79 (11) ◽  
pp. 6610-6619 ◽  
Author(s):  
M. K. Lewinski ◽  
D. Bisgrove ◽  
P. Shinn ◽  
H. Chen ◽  
C. Hoffmann ◽  
...  
Keyword(s):  
Human Immunodeficiency Virus ◽  
Fluorescent Protein ◽  
Centromeric Heterochromatin ◽  
Regulatory Sequences ◽  
Hiv Transcription ◽  
Genome Wide ◽  
A Genome ◽  
Immunodeficiency Virus ◽  
Hiv 1 ◽  
In Cells

ABSTRACT We have investigated regulatory sequences in noncoding human DNA that are associated with repression of an integrated human immunodeficiency virus type 1 (HIV-1) promoter. HIV-1 integration results in the formation of precise and homogeneous junctions between viral and host DNA, but integration takes place at many locations. Thus, the variation in HIV-1 gene expression at different integration sites reports the activity of regulatory sequences at nearby chromosomal positions. Negative regulation of HIV transcription is of particular interest because of its association with maintaining HIV in a latent state in cells from infected patients. To identify chromosomal regulators of HIV transcription, we infected Jurkat T cells with an HIV-based vector transducing green fluorescent protein (GFP) and separated cells into populations containing well-expressed (GFP-positive) or poorly expressed (GFP-negative) proviruses. We then determined the chromosomal locations of the two classes by sequencing 971 junctions between viral and cellular DNA. Possible effects of endogenous cellular transcription were characterized by transcriptional profiling. Low-level GFP expression correlated with integration in (i) gene deserts, (ii) centromeric heterochromatin, and (iii) very highly expressed cellular genes. These data provide a genome-wide picture of chromosomal features that repress transcription and suggest models for transcriptional latency in cells from HIV-infected patients.

scholarly journals 1592U89, a novel carbocyclic nucleoside analog with potent, selective anti-human immunodeficiency virus activity.

1997 ◽  
Vol 41 (5) ◽  
pp. 1082-1093 ◽  
Author(s):  
S M Daluge ◽  
S S Good ◽  
M B Faletto ◽  
W H Miller ◽  
M H St Clair ◽  
...  
Keyword(s):  
Human Immunodeficiency Virus ◽  
Oral Bioavailability ◽  
Human Peripheral Blood ◽  
Cross Resistance ◽  
Immunodeficiency Virus ◽  
Carbocyclic Nucleoside ◽  
Hiv 1 ◽  
In Cells

1592U89, (-)-(1S,4R)-4-[2-amino-6-(cyclopropylamino)-9H-purin-9-yl]-2-cyclo pentene-1-methanol, is a carbocyclic nucleoside with a unique biological profile giving potent, selective anti-human immunodeficiency virus (HIV) activity. 1592U89 was selected after evaluation of a wide variety of analogs containing a cyclopentene substitution for the 2'-deoxyriboside of natural deoxynucleosides, optimizing in vitro anti-HIV potency, oral bioavailability, and central nervous system (CNS) penetration. 1592U89 was equivalent in potency to 3'-azido-3'-deoxythymidine (AZT) in human peripheral blood lymphocyte (PBL) cultures against clinical isolates of HIV type 1 (HIV-1) from antiretroviral drug-naive patients (average 50% inhibitory concentration [IC50], 0.26 microM for 1592U89 and 0.23 microM for AZT). 1592U89 showed minimal cross-resistance (approximately twofold) with AZT and other approved HIV reverse transcriptase (RT) inhibitors. 1592U89 was synergistic in combination with AZT, the nonnucleoside RT inhibitor nevirapine, and the protease inhibitor 141W94 in MT4 cells against HIV-1 (IIIB). 1592U89 was anabolized intracellularly to its 5'-monophosphate in CD4+ CEM cells and in PBLs, but the di- and triphosphates of 1592U89 were not detected. The only triphosphate found in cells incubated with 1592U89 was that of the guanine analog (-)-carbovir (CBV). However, the in vivo pharmacokinetic, distribution, and toxicological profiles of 1592U89 were distinct from and improved over those of CBV, probably because CBV itself was not appreciably formed from 1592U89 in cells or animals (<2%). The 5'-triphosphate of CBV was a potent, selective inhibitor of HIV-1 RT, with Ki values for DNA polymerases (alpha, beta, gamma, and epsilon which were 90-, 2,900-, 1,200-, and 1,900-fold greater, respectively, than for RT (Ki, 21 nM). 1592U89 was relatively nontoxic to human bone marrow progenitors erythroid burst-forming unit and granulocyte-macrophage CFU (IC50s, 110 microM) and human leukemic and liver tumor cell lines. 1592U89 had excellent oral bioavailability (105% in the rat) and penetrated the CNS (rat brain and monkey cerebrospinal fluid) as well as AZT. Having demonstrated an excellent preclinical profile, 1592U89 has progressed to clinical evaluation in HIV-infected patients.

scholarly journals Inhibition of CD3/CD28-Mediated Activation of the MEK/ERK Signaling Pathway Represses Replication of X4 but Not R5 Human Immunodeficiency Virus Type 1 in Peripheral Blood CD4+T Lymphocytes

2000 ◽  
Vol 74 (6) ◽  
pp. 2558-2566 ◽  
Author(s):  
Waldemar Popik ◽  
Paula M. Pitha
Keyword(s):  
Human Immunodeficiency Virus ◽  
T Lymphocytes ◽  
Human Immunodeficiency Virus Type ◽  
Peripheral Blood ◽  
Erk Signaling ◽  
Erk Pathway ◽  
Immunodeficiency Virus ◽  
Hiv 1 ◽  
In Cells

ABSTRACT Binding of human immunodeficiency virus type 1 (HIV-1) to CD4 receptors induces multiple cellular signaling pathways, including the MEK/ERK cascade. While the interaction of X4 HIV-1 with CXCR4 does not seem to activate this pathway, viruses using CCR5 for entry efficiently activate MEK/ERK kinases (W. Popik, J. E. Hesselgesser, and P. M. Pitha, J. Virol. 72:6406–6413, 1998; W. Popik and P. M. Pitha, Virology 252:210–217, 1998). Since the importance of MEK/ERK in the initial steps of viral replication is poorly understood, we have examined the role of MEK/ERK signaling in the CD3- and CD28 (CD3/CD28)-mediated activation of HIV-1 replication in resting peripheral blood CD4+ T lymphocytes infected with X4 or R5 HIV-1. We have found that the MEK/ERK inhibitor U0126 selectively inhibited CD3/CD28-stimulated replication of X4 HIV-1, while it did not affect the replication of R5 HIV-1. Inhibition of the CD3/CD28-stimulated MEK/ERK pathway did not affect the formation of the early proviral transcripts in cells infected with either X4 or R5 HIV-1, indicating that virus reverse transcription is not affected in the absence of MEK/ERK signaling. In contrast, the levels of nuclear provirus in cells infected with X4 HIV-1, detected by the formation of circular proviral DNA, was significantly lower in cells stimulated in the presence of MEK/ERK inhibitor than in the absence of the inhibitor. However, in cells infected with R5 HIV-1, the inhibition of the MEK/ERK pathway did not affect nuclear localization of the proviral DNA. These data suggest that the nuclear import of X4, but not R5, HIV-1 is dependent on a CD3/CD28-stimulated MEK/ERK pathway.

scholarly journals Human Immunodeficiency Virus Env-Independent Infection of Human CD4− Cells

2000 ◽  
Vol 74 (23) ◽  
pp. 10994-11000 ◽  
Author(s):  
Shen Pang ◽  
Duan Yu ◽  
Dong Sung An ◽  
Gayle C. Baldwin ◽  
Yiming Xie ◽  
...  
Keyword(s):  
Human Immunodeficiency Virus ◽  
Cell Lines ◽  
Fluorescent Protein ◽  
Vaccine Development ◽  
Alternative Pathway ◽  
Neutralizing Antibody ◽  
Green Fluorescent Protein Gene ◽  
Immunodeficiency Virus ◽  
Green Fluorescent ◽  
Hiv 1

ABSTRACT CD4− epithelial cells covering mucosal surfaces serve as the primary barrier to prevent human immunodeficiency virus type 1 (HIV-1) infection. We used HIV-1 vectors carrying the enhanced green fluorescent protein gene as a reporter gene to demonstrate that HIV-1 can infect some CD4− human epithelial cell lines with low but significant efficiencies. Importantly, HIV-1 infection of these cell lines is independent of HIV-1 envelope proteins. The Env-independent infection of CD4− cells by HIV-1 suggests an alternative pathway for HIV-1 transmission. Even on virions bearing Env, a neutralizing antibody directed against gp120 is incapable of neutralizing the infection of these cells, thus raising potential implications for HIV-1 vaccine development.

scholarly journals CXCR4 Is Down-Regulated in Cells Infected with the CD4-Independent X4 Human Immunodeficiency Virus Type 1 Isolate m7NDK

2001 ◽  
Vol 75 (1) ◽  
pp. 439-447 ◽  
Author(s):  
Susana T. Valente ◽  
Chantal Chanel ◽  
Julie Dumonceaux ◽  
René Olivier ◽  
Stephano Marullo ◽  
...  
Keyword(s):  
Human Immunodeficiency Virus ◽  
Human Immunodeficiency Virus Type ◽  
Virus Type ◽  
Down Regulation ◽  
Immunodeficiency Virus ◽  
Cxcr4 Mrna ◽  
Infected Cells ◽  
Hiv 1 ◽  
In Cells

ABSTRACT Macrophages and T cells infected in vitro with CD4-dependent human immunodeficiency virus type 1 (HIV-1) isolates have reduced levels of CD4 protein, a phenomenon involved in retroviral interference. We have previously characterized the first CD4-independent HIV-1 X4 isolate m7NDK, which directly interacts with CXCR4 through its mutated gp120. We thus investigate CXCR4 expression in cells infected with this m7NDK CXCR4-dependent HIV-1 mutant. We present evidence of the down-regulation of CXCR4 membrane expression in CD4-positive or -negative cells chronically infected with the HIV-1 m7NDK, a phenomenon which is not observed in the CD4-dependent HIV-1 NDK parental strain. This down-regulation of CXCR4 was demonstrated by fluorescence-activated cell sorter analysis and was confirmed by the absence of CXCR4 functionality in m7NDK-infected cells, independently of the presence of CD4 protein. Furthermore, a drastic reduction of the intracellular level of CXCR4 protein was also observed. Reduced levels of CXCR4 mRNA transcripts were found in m7NDK-infected HeLa and CEM cells, reduced levels that could not be attributed to a reduced stability of CXCR4 mRNA. Down-regulation of CXCR4 on m7NDK-infected cells may thus be explained by transcriptional regulation.

scholarly journals Naturally Occurring Human Immunodeficiency Virus Type 1 Long Terminal Repeats Have a Frequently Observed Duplication That Binds RBF-2 and Represses Transcription

1998 ◽  
Vol 72 (8) ◽  
pp. 6465-6474 ◽  
Author(s):  
Mario Clemente Estable ◽  
Brendan Bell ◽  
Martin Hirst ◽  
Ivan Sadowski
Keyword(s):  
Human Immunodeficiency Virus ◽  
Human Immunodeficiency Virus Type ◽  
Virus Type ◽  
Binding Sites ◽  
Naturally Occurring ◽  
Immunodeficiency Virus ◽  
Aids Study ◽  
Hiv 1 ◽  
In Cells

ABSTRACT Approximately 38% of human immunodeficiency virus type 1 (HIV-1)-infected patients within the Vancouver Lymphadenopathy-AIDS Study have proviruses bearing partial 15- to 34-nucleotide duplications upstream of the NF-κB binding sites within the 5′ long terminal repeat (LTR). This most frequent naturally occurring length polymorphism (MFNLP) of the HIV-1 5′ LTR encompasses potential binding sites for several candidate transcription factors, including TCF-1α/hLEF, c-Ets, AP-4, and Ras-responsive binding factor 2 (RBF-2) (M. C. Estable et al., J. Virol. 70:4053–4062, 1996). RBF-2 and an apparently related factor, RBF-1, bind to at least fourcis elements within the LTR which are required for full transcriptional responsiveness to protein-tyrosine kinases and v-Ras (B. Bell and I. Sadowski, Oncogene 13:2687–2697, 1996). Here we demonstrate that representative MFNLPs from two patients specifically bind RBF-2. In both cases, deletion of the MFNLP caused elevated LTR-directed transcription in cells expressing RBF-2 but not in cells with undetectable RBF-2. RBF-1, but not RBF-2, appears to contain the Ets transcription factor family member GABPα/GABPβ1. Taken together with the fact that every MFNLP from a comparative study of over 500 LTR sequences from 42 patients contains a predicted binding site for RBF-2, our data suggest that the MFNLP is selected in vivo because it provides a duplicated RBF-2 cis element, which may limit transcription in monocytes and activated T cells.

scholarly journals Effect of tamoxifen on regulation of viral replication and human immunodeficiency virus (HIV) long terminal repeat-directed transcription in cells chronically infected with HIV-1

Blood ◽  
1990 ◽  
Vol 75 (3) ◽  
pp. 696-703 ◽  
Author(s):  
J Laurence ◽  
H Cooke ◽  
SK Sikder
Keyword(s):  
Human Immunodeficiency Virus ◽  
Viral Replication ◽  
Long Terminal Repeat ◽  
Terminal Repeat ◽  
Consensus Sequences ◽  
Kinase C ◽  
Immunodeficiency Virus ◽  
Cellular Dna ◽  
Hiv 1 ◽  
In Cells

The protein kinase C (PKC) activator phorbol myristate acetate (PMA) was used to upregulate viral replication in a clone of promonocytic cells chronically infected with human immunodeficiency virus (HIV)-1. Induction of virus could be inhibited by the triphenylethylene anti- estrogen tamoxifen at concentrations that had minimal effects on cellular DNA synthetic responses and cell cycle kinetics. This effect correlated with tamoxifen's ability to block PMA-mediated enhancement of HIV-promoter-driven transactivation in cells of monocyte and CD4+ T- lymphocyte lineages. No interference with a primary infection was noted. Tamoxifen's mechanism of action may relate both to its capacity to inhibit PKC and to consensus sequences for gonadal steroid responsive elements in the HIV long terminal repeat, as it was able to partially inhibit another HIV activator, 5-azacytidine, which does not modulate PKC function. The finding that regulation of HIV in a model for low-level chronic or latent infection is amenable to a nonimmunosuppressive steroid antagonist may suggest approaches to pharmacologic intervention early in HIV infection.

scholarly journals Effect of tamoxifen on regulation of viral replication and human immunodeficiency virus (HIV) long terminal repeat-directed transcription in cells chronically infected with HIV-1

Blood ◽  
1990 ◽  
Vol 75 (3) ◽  
pp. 696-703 ◽  
Author(s):  
J Laurence ◽  
H Cooke ◽  
SK Sikder
Keyword(s):  
Human Immunodeficiency Virus ◽  
Viral Replication ◽  
Long Terminal Repeat ◽  
Terminal Repeat ◽  
Consensus Sequences ◽  
Kinase C ◽  
Immunodeficiency Virus ◽  
Cellular Dna ◽  
Hiv 1 ◽  
In Cells

Abstract The protein kinase C (PKC) activator phorbol myristate acetate (PMA) was used to upregulate viral replication in a clone of promonocytic cells chronically infected with human immunodeficiency virus (HIV)-1. Induction of virus could be inhibited by the triphenylethylene anti- estrogen tamoxifen at concentrations that had minimal effects on cellular DNA synthetic responses and cell cycle kinetics. This effect correlated with tamoxifen's ability to block PMA-mediated enhancement of HIV-promoter-driven transactivation in cells of monocyte and CD4+ T- lymphocyte lineages. No interference with a primary infection was noted. Tamoxifen's mechanism of action may relate both to its capacity to inhibit PKC and to consensus sequences for gonadal steroid responsive elements in the HIV long terminal repeat, as it was able to partially inhibit another HIV activator, 5-azacytidine, which does not modulate PKC function. The finding that regulation of HIV in a model for low-level chronic or latent infection is amenable to a nonimmunosuppressive steroid antagonist may suggest approaches to pharmacologic intervention early in HIV infection.

scholarly journals Genetic Recombination between Human Immunodeficiency Virus Type 1 (HIV-1) and HIV-2, Two Distinct Human Lentiviruses

2007 ◽  
Vol 82 (4) ◽  
pp. 1923-1933 ◽  
Author(s):  
Kazushi Motomura ◽  
Jianbo Chen ◽  
Wei-Shau Hu
Keyword(s):  
Human Immunodeficiency Virus ◽  
Human Immunodeficiency Virus Type ◽  
Virus Type ◽  
Fluorescent Protein ◽  
Genetic Recombination ◽  
Green Fluorescent Protein Gene ◽  
Low Frequencies ◽  
Immunodeficiency Virus ◽  
Hiv 1

ABSTRACT Human immunodeficiency virus type 1 (HIV-1) and HIV-2 are genetically distinct viruses that each can cause AIDS. Approximately 1 million people are infected with both HIV-1 and HIV-2. Additionally, these two viruses use the same receptor and coreceptors and can therefore infect the same target cell populations. To explore potential genetic interactions, we first examined whether RNAs from HIV-1 and HIV-2 can be copackaged into the same virion. We used modified near-full-length viruses that each contained a green fluorescent protein gene (gfp) with a different inactivating mutation. Thus, a functional gfp could be reconstituted via recombination, which was used to detect the copackaging of HIV-1 and HIV-2 RNAs. The GFP-positive (GFP+) phenotype was detected in approximately 0.2% of the infection events, which was 35-fold lower than the intrasubtype HIV-1 rates. We isolated and characterized 54 GFP+ single-cell clones and determined that all of them contained proviruses with reconstituted gfp. We then mapped the general structures of the recombinant viruses and characterized the recombination junctions by DNA sequencing. We observed several different recombination patterns, including those that had crossovers only in gfp. The most common hybrid genomes had heterologous long terminal repeats. Although infrequent, crossovers in the viral sequences were also identified. Taken together, our study demonstrates that HIV-1 and HIV-2 can recombine, albeit at low frequencies. These observations indicate that multiple factors are likely to restrict the generation of viable hybrid HIV-1 and HIV-2 viruses. However, considering the large coinfected human population and the high viral load in patients, these rare events could provide the basis for the generation of novel human immunodeficiency viruses.

scholarly journals Loss of the Brm-Type SWI/SNF Chromatin Remodeling Complex Is a Strong Barrier to the Tat-Independent Transcriptional Elongation of Human Immunodeficiency Virus Type 1 Transcripts

2009 ◽  
Vol 83 (22) ◽  
pp. 11569-11580 ◽  
Author(s):  
Taketoshi Mizutani ◽  
Aya Ishizaka ◽  
Mariko Tomizawa ◽  
Takuya Okazaki ◽  
Nobutake Yamamichi ◽  
...  
Keyword(s):  
Human Immunodeficiency Virus ◽  
Cell Lines ◽  
Competent Cell ◽  
Transcriptional Elongation ◽  
Gfp Expression ◽  
Proviral Integration ◽  
Hiv Transcription ◽  
Immunodeficiency Virus ◽  
Hiv 1

ABSTRACT To elucidate the epigenetic regulation of Tat-independent human immunodeficiency virus (HIV) transcription following proviral integration, we constructed an HIV type 1 (HIV-1)-based replication-defective viral vector that expresses a reporter green fluorescent protein (GFP) product from its intact long terminal repeat (LTR). We transduced this construct into human tumor cell lines that were either deficient in or competent for the Brm-type SWI/SNF complex. One day after transduction, single cells that expressed GFP were sorted, and the GFP expression profiles originating from each of these clones were analyzed. Unlike clones of the SWI/SNF-competent cell line, which exhibited clear unimodal expression patterns in all cases, many clones originating from Brm-deficient cell lines either showed a broad-range distribution of GFP expression or were fully silenced. The resorting of GFP-negative populations of these isolated clones showed that GFP silencing is either reversible or irreversible depending upon the proviral integration sites. We further observed that even in these silenced clones, proviral gene transcription initiates to accumulate short transcripts of around 60 bases in length, but no elongation occurs. We found that this termination is caused by tightly closed nucleosome-1 (nuc-1) at the 5′ LTR. Also, nuc-1 is remodeled by exogenous Brm in some integrants. From these results, we propose that Brm is required for the occasional transcriptional elongation of the HIV-1 provirus in the absence of Tat. Since the Brm-type SWI/SNF complex is expressed at marginal levels in resting CD4+ T cells and is drastically induced upon CD4+ T-cell activation, we speculate that it plays crucial roles in the early Tat-independent phase of HIV transcription in affected patients.

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