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Query: UMLS:C0019693 (HIV)
 170,526 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The HIV-1 encoded regulatory Rev protein acts to selectively increase the cytoplasmic concentration of incompletely spliced viral mRNAs through interaction with the Rev responsive element (RRE). In addition, the Rev activation domain, believed to be a nuclear export sequence, has been shown to modulate the export of non-RRE containing RNAs (e.g. 5S rRNA, splicesomal U snRNAs). Recent evidence suggests Rev activity depends on interactions with cellular cofactors, leading to speculation that Rev utilizes a cellular RNA and/or a protein export pathway. Rev interactions with cellular cofactors could lead to sequestration of those cofactors from normal cellular activities, suggesting potential Rev effects on cellular gene products and their resultant activity. We have examined the role of Rev in modulating the expression of cellular gene products. Through transient cotransfection assays, we observed a consistent and significant decrease in the levels of luciferase and B-galactosidase activity in the presence of a Rev expressing construct. Cell fractionation studies demonstrated the nuclear retention of the luciferase gene transcripts. Surprisingly, similar effects were observed on constitutively expressed RNAs such as gamma-actin transcripts, and the 18S and 28S rRNAs. These results suggest Rev can disrupt the nuclear export of multiple classes of RNAs.
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PMID:Effects of the human immunodeficiency virus type 1 Rev protein on reporter gene and host T-cell gene expression. 944 32

Two peptide segments designated LLP1 (residues 828-855) and LLP2 (residues 768-788) of the HIV-1 transmembrane (TM) envelope protein display structural and functional properties of calmodulin (CaM) binding. These LLP segments may contribute to cytopathogenesis by binding cellular CaM and inhibiting normal CaM-regulated signal transduction pathways. To determine whether these peptides could interrupt signal transduction in vivo, a cellular assay which uses a reporter gene linked to the nuclear factor of activated T cells (NF-AT) was used. Signal transduction perturbation was tested by exogenous addition of LLPs, W-7 or ionomycin; the LLPs inhibited NF-AT-mediated signal transduction as measured by reduced reporter activity. The LLP inhibition profile of NF-AT-driven luciferase activity was similar to the CaM inhibitor W-7. This was in direct contrast to ionomycin, a mobile calcium ion carrier which caused a significant increase in luciferase activity. These findings are consistent with the hypothesis that the CaM-binding properties of TM may contribute to defects in signal transduction leading to the T-cell anergy observed in patients infected with HIV-1.
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PMID:Interruption of T-cell signal transduction by lentivirus lytic peptides from HIV-1 transmembrane protein. 949 94

We have recently demonstrated that the parasite Leishmania donovani and its surface molecule, lipophosphoglycan (LPG), can activate HIV-1 replication in monocytoid cells. Our present interest was to determine whether LPG could also up-regulate HIV-1 transcription in T cells. Using a CD4-positive human lymphoid T cell line (1G5) containing a stably integrated HIV-1 long terminal repeat (LTR)-luciferase construct, we found that LPG is a potent inducer of HIV-1 LTR activity. Treatment of 1G5 cells with signaling antagonists revealed that protein tyrosine kinase- and protein kinase A-dependent pathways were actively participating in the LPG-induced enhancement of HIV-1 LTR-driven activity. Transfection of Jurkat E6.1 cells with plasmids containing wild-type and nuclear factor-kappaB (NF-kappaB)-mutated HIV-1 LTR-luciferase constructs has suggested a role for NF-kappaB binding sites in the LPG-mediated induction of HIV-1 LTR activity. An LPG-induced binding factor specific to the NF-kappaB consensus sequences could be observed using electrophoretic mobility shift assay. Finally, transfection experiments performed with a vector containing HIV-1 kappaB binding sites only showed similar LPG-mediated induction, which was abrogated by sodium salicylate, a known NF-kappaB inhibitor. We thus demonstrate that the LPG-mediated induction of HIV-1 LTR activity in T cells involves several second messengers culminating in activation of HIV-1 LTR-driven transcription via NF-kappaB-binding consensus sequences. In conclusion, these results reinforce the idea that L. donovani is a putative cofactor in HIV-1 pathogenesis.
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PMID:The lipophosphoglycan of Leishmania donovani up-regulates HIV-1 transcription in T cells through the nuclear factor-kappaB elements. 951 Jan 91

Replication of human immunodeficiency virus type 1 (HIV-1) is regulated by a host transcription factor, nuclear factor kappaB (NF-kappaB). NF-kappaB belongs to a group of inducible transcription factors and its activity is regulated by multiple cellular signal transduction pathways, including kinases. These kinases are known to be involved in signal-induced NF-kappaB activation and in the induction of HIV-1 gene expression from latently infected cells. In this study we have examined the effect of a newly developed serine/threonine kinase inhibitor, fasudil hydrochloride (FH), on the replication of HIV-1. Although FH was initially developed as a compound that inhibited a myosin light chain kinase (MLCK) and had been approved for clinical use in the treatment of vasospasm after subarachnoid hemorrhage, this study shows its efficacy in blocking HIV-1 replication in latently infected patients. When FH was added to monocytic cell lines latently infected with HIV-1, U1 and OM10.1, the induction of HIV-1 replication by TNF-alpha was blocked at noncytotoxic doses. The IC50 values of HIV-1 induction by FH were 9.3 and 24 microM for U1 and OM10.1, respectively. Because FH could block TNF-alpha-induced, NF-kappaB-dependent gene expression, as examined by the transient luciferase expression assay, the effect of FH was considered to be due to the blocking of the signal transduction pathway of NF-kappaB activation. Although the in vivo effect of FH in blocking HIV-1 induction is not yet known, these findings indicate the feasibility of clinical use of FH and its derivatives in decreasing viral load to prevent clinical development of acquired immunodeficiency syndrome (AIDS) among HIV-1-infected individuals.
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PMID:Inhibition of human immunodeficiency virus type 1 replication by a bioavailable serine/threonine kinase inhibitor, fasudil hydrochloride. 951 89

Macrophages recognize and are activated by unmethylated CpG motifs in bacterial DNA. Here we demonstrate that production of nitric oxide (NO) from murine RAW 264 macrophages and bone marrow-derived macrophages (BMM) in response to bacterial DNA is absolutely dependent on interferon-gamma (IFN-gamma) priming. Similarly, arginine uptake and expression of the inducible nitric oxide synthase (iNOS) gene in response to bacterial DNA in BMM occurred only after IFN-gamma priming. In contrast, mRNA for the cationic amino acid transporter, CAT2, was induced by plasmid DNA alone, and priming with IFN-gamma had no effect on this response. Tumor necrosis factor-alpha (TNF-alpha) release from RAW 264 and BMM in response to bacterial DNA was augmented by IFN-gamma pretreatment. In a stably transfected HIV-1 long terminal repeat (LTR) luciferase RAW 264 cell line, IFN-gamma and bacterial DNA synergized in activation of the HIV-1 LTR. Bacterial DNA has been shown to induce IFN-gamma production in vivo as an indirect consequence of interleukin-12 (IL-12) and TNF-alpha production from macrophages. The results herein suggest the existence of a self-amplifying loop that may have implications for therapeutic applications of bacterial DNA.
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PMID:IFN-gamma primes macrophage responses to bacterial DNA. 956 29

Primary cultured human macrophages are difficult to transfect. We have developed a DEAE-dextran DNA transfection method that mediates the reproducible transfection of primary cultured adherent human macrophages. Three factors essential for successful transfection were identified: DEAE-dextran concentration, the quantity of DNA per transfection and the incubation time of the macrophages with the transfection medium. Maximum levels of luciferase expression were attained within 24 h and maintained for at least 56 h after transfection. While serum in the transfection medium attenuated transfection, the treatment of the macrophages with chloroquine, DMSO, or glycerol did not enhance transfection within this system. A CMV enhancer/promoter mediated substantially greater luciferase expression in the macrophages than either HIV or RSV LTRs. DEAE-dextran facilitated superior transfection compared to either cationic liposome and calcium phosphate methods, and was more practical compared to electroporation for multiple transfections. This transfection protocol provides a simple, inexpensive, reproducible method for the evaluation of gene expression in primary cultured adherent human macrophages.
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PMID:A novel method for DEAE-dextran mediated transfection of adherent primary cultured human macrophages. 961 33

A new reporter system has been developed for measuring translation coupling efficiency of recoding mechanisms such as frameshifting or readthrough. A recoding test sequence is cloned in between the renilla and firefly luciferase reporter genes and the two luciferase activities are subsequently measured in the same tube. The normalized ratio of the two activities is proportional to the efficiency with which the ribosome "reads" the recoding signal making the transition from one open reading frame to the next. The internal control from measuring both activities provides a convenient and reliable assay of efficiency. This is the first enzymatic dual reporter assay suitable for in vitro translation. Translation signals can be tested in vivo and in vitro from a single construct, which allows an intimate comparison between the two systems. The assay is applicable for high throughput screening procedures. The dual-luciferase reporter system has been applied to in vivo and in vitro recoding of HIV-1 gag-pol, MMTV gag-pro, MuLV gag-pol, and human antizyme.
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PMID:A dual-luciferase reporter system for studying recoding signals. 963 Feb 53

Tuberculosis has emerged as an epidemic, extended by the large number of individuals infected with human immunodeficiency virus type 1 (HIV-1). The major goal of this study was to determine whether the mycobacterial cell wall component mannose-capped lipoarabinomannan (ManLAM) of Mycobacterium tuberculosis (M. tuberculosis) could activate transcription of HIV-1 in T cells with the use of an in vitro cell culture system. These experiments are of prime importance considering that CD4-expressing T lymphocytes represent the major virus reservoir in the peripheral blood of infected individuals. Using the 1G5 cell line harbouring the luciferase reporter gene under the control of the HIV-1 LTR, it was first found that culture protein filtrates (CFP) from M. tuberculosis or purified ManLAM could activate HIV-1 LTR-dependent gene expression unlike similarly prepared CFP extracts devoid of ManLAM. The implication of protein tyrosine kinase(s), protein kinase A and/or protein kinase C was highlighted by the abrogation of the ManLAM-mediated activation of HIV-1 LTR-driven gene expression using herbimycin A and H7. It was also determined, using electrophoresis mobility shift assays, that M. tuberculosis ManLAM led to the nuclear translocation of the transcription factor NF-kappaB. M. tuberculosis ManLAM resulted in clear induction of the luciferase gene placed under the control of the wild-type, but not the kappaB-mutated, HIV-1 LTR region. Finally, the ManLAM-mediated activation of HIV-1 LTR transcription was found to be independent of the autocrine or paracrine action of endogenous TNF-alpha. The results suggest that M. tuberculosis can upregulate HIV-1 expression in T cells and could thus have the potential to influence the pathogenesis of HIV-1 infection.
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PMID:Mycobacterium tuberculosis mannose-capped lipoarabinomannan can induce NF-kappaB-dependent activation of human immunodeficiency virus type 1 long terminal repeat in T cells. 963 75

The HIV-1 LTR promoter proximal G/C box array has been demonstrated to function by interacting with the Sp1 transcription factor family whose members can act as either activators or repressors of transcription. In this regard, we have examined the interaction of the HIV-1 Sp binding sites with nuclear factors that are present in cell types that support HIV-1 replication, including those of lymphocytic, monocytic, and astrocytic origin. As determined by electrophoretic mobility shift (EMS) competition analyses using oligonucleotides containing the sequences of each of the Sp1 sites of HIV-1 strain LAI, the NF-kappaB-proximal Sp site (site III) displayed the highest binding activity compared to sites I and II with regard to Sp1 and related factors present in lymphocytic (Jurkat) and astrocytic (U-373 MG) nuclear extracts. Sp1 and two Sp3 isoforms were detected as the primary cellular constituents of DNA-protein complexes formed with the NF-kappaB-proximal site. Only modest differences in Sp1:Sp3 binding ratios were observed when this site was reacted with either astrocytic or lymphocytic nuclear extract. However, when nuclear extracts derived from two monocytic cell types that differ in the degree of differentiation were reacted with the HIV-1 LAI Sp site III, a large difference in Sp1 and Sp3 binding was observed. To determine if naturally occurring and replication-competent strains of HIV-1 contain base pair alterations within the Sp elements that affect the ability of the site to interact with Sp1 and related factors, a series of Sp site III variants were constructed and examined by EMS analyses. One of these sites, obtained from the published sequence of the YU-2 strain (a brain-derived macrophage tropic strain of HIV-1), displayed almost no Sp1 or Sp3 binding activity as a result of a single base pair alteration in Sp site III. This base-pair alteration, when placed in the context of an HIV-1 LAI LTR-luciferase construct, resulted in a 40-50% reduction in LTR activity in transiently transfected Jurkat and U-373 MG cells. Overall, these results suggest that specific G/C box sequence alterations present in the brain-derived HIV-1 variant YU-2, or possibly other brain-derived variants, may exhibit altered replication properties as a result of the low affinity of the NF-kappaB-proximal G/C box for members of the Sp transcription factor family.
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PMID:Sp1 and related factors fail to interact with the NF-kappaB-proximal G/C box in the LTR of a replication competent, brain-derived strain of HIV-1 (YU-2). 963 74

Sulfatide (3'sulfogalactosylceramide) is the natural sulfated derivative of galactosylceramide (GalCer), a glycosphingolipid receptor allowing HIV-1 infection of CD4-negative cells from neural and intestinal tissues. The incorporation of exogenous sulfatide into the plasma membrane of HT-29 (a CD4-/GalCer+/CXCR4+ human intestinal cell line) or RD (CD4-/GalCer-/ CXCR4+ human rhabdomyosarcoma) resulted in a dose-dependent inhibition of HIV-1 infection. Experiments with luciferase reporter viruses pseudotyped with HIV-1 or amphotropic murine leukemia virus envelopes demonstrated that sulfatide acts at the level of viral entry. Paradoxically, the transfer of sulfatide in the plasma membrane of various CD4- cells resulted in increased binding of HIV-1. Surface pressure measurements were conducted to study the interaction of gp120 with glycosphingolipid monolayers. The data showed that gp120 could penetrate into a monomolecular film of GalCer, confirming the role of this glycosphingolipid as a functional receptor for HIV-1. In contrast, the insertion of gp120 into a monolayer of sulfatide was very limited. Moreover, the incorporation of sulfatide in a monomolecular film of GalCer specifically inhibited the penetration of gp120. In conclusion, these data show that sulfatide mediates gp120 binding but, in marked contrast with GalCer, is not able to initiate the fusion event.
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PMID:Sulfatide inhibits HIV-1 entry into CD4-/CXCR4+ cells. 965 40


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