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

Basal transcription of the HIV-1 genome is controlled by a variety of ubiquitous and inducible regulatory factors, some with the ability to associate with the viral DNA sequences within the promoter spanning the long terminal repeat (LTR). In this report we demonstrate that activation of the HIV-1 promoter through the inducible DNA binding NF-kappaB transcription factors can be affected by cdk9 in human astrocytic cells. Our results show that ectopic expression of cdk9, but not its mutant variant which lacks the domain responsible for its kinase activity, augments transcription of the LTR. Moreover, we demonstrate that induction of the NF-kappaB pathway by PMA, or overexpression of its subunits including p50/p65 have a negative effect on the ability of cdk9 to stimulate viral gene transcription in these cells. Results from band-shift experiments demonstrated significant suppression of p50/p65 association to its DNA target motif by cdk9. Further, data from GST pull-down and combined immunoprecipitation/Western blot analysis of the protein extracts from cells expressing cdk9, p50 and p65 have revealed the interaction of cdk9 with both p50 and p65 in the absence of DNA containing the kappaB motif. All of these observations led us to conclude that the interaction of cdk9 with the NF-kappaB factors can determine the ability of NF-kappaB to modulate HIV-1 gene transcription.
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PMID:Interplay between cdk9 and NF-kappaB factors determines the level of HIV-1 gene transcription in astrocytic cells. 1217 51

The transcription factor NF-kappaB is regulated by the IkappaB family of proteins. The nonphosphorylatable, nondegradable superrepressor IkappaBalpha (srIkappaBalpha) mutant is a potent inhibitor of NF-kappaB activity when expressed in cells. We generated a form of srIkappaBalpha in which its N terminus is fused to the protein transduction domain of HIV TAT (TAT-srIkappaBalpha). Purified TAT-srIkappaBalpha protein rapidly and efficiently entered HeLa or Jurkat T cells. TAT-srIkappaBalpha, when exogenously added to HeLa cells, inhibited in a dose-dependent manner TNF-alpha- or IL-1beta-induced NF-kappaB activation and binding of NF-kappaB to its consensus DNA sequence. TAT-srIkappaBalpha was coimmunoprecipitated with the p65 subunit of NF-kappaB, and this interaction was resistant to stimulation with IL-1beta. Therefore, TAT-srIkappaBalpha-mediated inhibition could result from its nonreversible binding and sequestration of endogenous NF-kappaB. In contrast, exogenously added TAT-srIkappaBalpha did not inhibit IL-1beta-induced activation of extracellular signal-regulated kinase, c-Jun N-terminal kinase, or p38 mitogen-activated protein kinases or the phosphorylation and degradation of endogenous IkappaBalpha. These results identify a novel way for direct regulation of NF-kappaB activity in diverse cell types that may be useful for therapeutic purposes.
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PMID:Inhibition of NF-kappa B activity by a membrane-transducing mutant of I kappa B alpha. 1219 29

The transcription factor NF-kappaB plays a central role in the human immunodeficiency virus type 1 (HIV-1) activation pathway. HIV-1 transcription is also regulated by protein acetylation, since treatment with deacetylase inhibitors such as trichostatin A (TSA) or sodium butyrate (NaBut) markedly induces HIV-1 transcriptional activity of the long terminal repeat (LTR) promoter. Here, we demonstrate that TSA (NaBut) synergized with both ectopically expressed p50/p65 and tumor necrosis factor alpha/SF2 (TNF)-induced NF-kappaB to activate the LTR. This was confirmed for LTRs from subtypes A through G of the HIV-1 major group, with a positive correlation between the number of kappaB sites present in the LTRs and the amplitude of the TNF-TSA synergism. Mechanistically, TSA (NaBut) delayed the cytoplasmic recovery of the inhibitory protein IkappaBalpha. This coincided with a prolonged intranuclear presence and DNA binding activity of NF-kappaB. The physiological relevance of the TNF-TSA (NaBut) synergism was shown on HIV-1 replication in both acutely and latently HIV-infected cell lines. Therefore, our results open new therapeutic strategies aimed at decreasing or eliminating the pool of latently HIV-infected reservoirs by forcing viral expression.
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PMID:Synergistic activation of human immunodeficiency virus type 1 promoter activity by NF-kappaB and inhibitors of deacetylases: potential perspectives for the development of therapeutic strategies. 1236 51

The binding subunit of pertussis toxin (PTX-B) has been shown recently to inhibit the entry and postentry events in HIV-1 replication in primary T lymphocytes and monocyte-derived macrophages. While the effect of PTX-B on HIV-1 entry was shown to involve CCR5 desensitization, the mechanism of postentry inhibition remained unclear. In T lymphocytes, PTX-B affected transcription or stability of Tat-stimulated HIV-1 mRNAs. In this study, we sought to identify the mechanism of postentry inhibition of HIV-1 replication by PTX-B in U-937 promonocytic cells. We demonstrate that in these cells PTX-B inhibits expression of luciferase reporter gene controlled by the HIV-1 LTR promoter. This effect is Tat-independent and is not restricted to the HIV-1 LTR promoter. Instead, PTX-B activity is mediated through suppression of the cellular transcription factor, NF-kappaB. PTX-B inhibits phosphorylation and nuclear translocation of the p65 subunit of NF-kappaB. This effect is independent of the cytoplasmic NF-kappaB inhibitor, IkappaBalpha, as PTX-B stimulates phosphorylation and subsequent degradation of this protein. The suppressive activity of PTX-B on NF-kappaB p65 phosphorylation and nuclear translocation is delayed, suggesting that PTX-B signaling might initiate synthesis and cytoplasmic accumulation of a p65 phosphorylation inhibitor.
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PMID:B-oligomer of pertussis toxin inhibits HIV-1 LTR-driven transcription through suppression of NF-kappaB p65 subunit activity. 1242 28

Human immunodeficiency virus type 1 (HIV-1) gene expression is regulated by both cellular transcription factors and Tat. The ability of Tat to stimulate transcriptional elongation is dependent on its binding to TAR RNA in conjunction with cyclin T1 and CDK9. A variety of other cellular factors that bind to the HIV-1 long terminal repeat, including NF-kappaB, SP1, LBP, and LEF, are also important in the control of HIV-1 gene expression. Although these factors have been demonstrated to regulate HIV-1 gene expression by both genetic and biochemical analysis, in most cases a direct in vivo demonstration of their role on HIV-1 replication has not been established. Recently, the efficacy of RNA interference in mammalian cells has been shown utilizing small interfering RNAs (siRNAs) to result in the specific degradation of host mRNAs and decreases the levels of their corresponding proteins. In this study, we addressed whether siRNAs directed against either HIV-1 tat or reverse transcriptase or the NF-kappaB p65 subunit could specifically decrease the levels of these proteins and thus alter HIV-1 replication. Our results demonstrate the specificity of siRNAs for decreasing the expression of these viral and cellular proteins and inhibiting HIV-1 replication. These studies suggest that RNA interference is useful in exploring the biological role of cellular and viral regulatory factors involved in the control of HIV-1 gene expression.
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PMID:RNA interference directed against viral and cellular targets inhibits human immunodeficiency Virus Type 1 replication. 1243 22

Treatment of OM10.1 cells latently infected with human immunodeficiency virus type 1 (HIV-1) with phorbol ester and calcium ionophore (A23187) induced virus replication which was blocked by N-Ac-Leu-Leu-norleucinal (ALLnL), a calpain inhibitor I, and not by lactacystin, a specific proteasome inhibitor. When the purified NF-kappa B/I kappa B complex was treated with mu-calpain, the specific DNA-binding activity was demonstrated by using electrophoretic mobility shift assay in vitro. This effect of mu-calpain was inhibited by ALLnL and calpastatin and not by lactacystin. In fact, we found that mu-calpain efficiently degraded I kappa B alpha. Furthermore, our Western blotting analysis has revealed that mu-calpain cleaves I kappa B alpha at its N-terminal and C-terminal regions that were previously reported to be involved in the interaction with NF-kappa B p65. These observations indicate that in monocyte/macrophage cells calcium signaling is involved in NF-kappa B activation through activation of calpain and thus calpain inhibitors may be effective in inhibiting the activation of latently infected HIV.
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PMID:Calpain is involved in the HIV replication from the latently infected OM10.1 cells. 1267 May 2

To explore the mechanism by which morphine promotes the incidence of HIV infection, we evaluated the regulatory role of morphine on the interferon-gamma (IFN-gamma) promoter in activated T cells from wild type and mu-opioid receptor knockout mice. Our results show that morphine inhibited anti-CD3/CD28-stimulated IFN-gamma promoter activity in a dose-dependent manner. Chronic morphine treatment of T cells increased intracellular cAMP. To evaluate the role of cAMP in morphine's modulatory function, the effects of dibutyryl cyclic AMP and forskolin were investigated. Both dibutyryl cyclic AMP and forskolin treatment inhibited IFN-gamma promoter activity. Treatment with pertussis toxin, but not with a protein kinase A inhibitor, antagonized morphine's inhibitory effects. Morphine inhibited phosphorylation of ERK1/2 and p38 MAPK; in addition, morphine treatment in the presence of either ERK1/2 or p38 MAPK inhibitor (PD98059 or SB203580) resulted in an additive inhibition of IFN-gamma promoter activity. The transcription factor activator protein-1, NF-kappaB, and nuclear factor of activated T cells (NFAT) were negatively regulated by morphine. Overexpression of NF-kappaB p65 rescued the inhibitory effect of morphine on IFN-gamma promoter activity. However, only when NFATc1 was co-overexpressed with c-fos was the inhibitory effect of morphine on IFN-gamma promoter counteracted. The inhibitory effects of morphine were not observed in T cells obtained from mu-opioid receptor knockout mice, suggesting that morphine modulation of IFN-gamma promoter activity is mediated through the mu-opioid receptor. In summary, our data indicate that morphine modulation of IFN-gamma promoter activity is mediated through two distinct cAMP-dependent pathways, the NF-kappaB signaling pathway and the ERK1/2, p38 MAPK, AP-1/NFAT pathway.
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PMID:Morphine negatively regulates interferon-gamma promoter activity in activated murine T cells through two distinct cyclic AMP-dependent pathways. 1284 91

NF-kappaB/IkappaB proteins play a major role in the transcriptional regulation of human immunodeficiency virus, type-1 (HIV-1). In the case of simian immunodeficiency virus (SIV) the cellular factors required for the viral transcriptional activation and replication in vivo remain undefined. Here, we demonstrate that the p50/p65 NF-kappaB transcription factors enhanced the Tat-mediated transcriptional activation of SIVmac239. In addition, IkappaB-alpha S32/36A, a proteolysis-resistant inhibitor of NF-kappaB, strongly inhibited the Tat-mediated transactivation of SIVmac239. Based on this evidence, we have generated a self-regulatory virus by endowing the genome of SIV-mac239 with IkappaB-alpha S32/36A; the resulting virus, SIVIkappaB-alpha S32/36A, was nef-deleted and expressed the NF-kappaB inhibitor. We show that SIVIkappaB-alpha S32/36A was highly and stably attenuated both in cell cultures and in vivo in rhesus macaque as compared with a nef-deleted control virus. Moreover, the high attenuation was associated with a robust immune response as measured by SIV-specific antibody production, tetramer, and intracellular IFN-gamma staining of SIV gag-specific T cells. These results underscore the crucial role of NF-kappaB/IkappaB proteins in the regulation of SIV replication both in cell cultures and in monkeys. Thus, inhibitors of NF-kappaB could efficiently counteract the SIV/HIV replication in vivo and may assist in developing novel approaches for AIDS vaccine and therapy.
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PMID:High attenuation and immunogenicity of a simian immunodeficiency virus expressing a proteolysis-resistant inhibitor of NF-kappaB. 1459 21

Nuclear factor kappaB (NF-kappaB) represents a family of inducible DNA-binding transcription factors whose activity is critical for expression of the HIV-1 genome in a broad range of cells. In addition to its interaction with the kappaB DNA sequence, the association of NF-kappaB subunits with other cellular proteins plays an important role in stimulation of HIV-1 gene transcription in astrocytic cells. Here, we utilized a yeast two-hybrid system to screen a cDNA library from a human astrocytic cell line and were able to isolate a partial cDNA belonging to a gene with an open reading frame of 1,871 amino acid residues which binds to both the p50 and p65 subunits of NF-kappaB. This gene, named NF-kappaB-binding protein (NFBP) is located on chromosome 10q24.2-25.1 and hybridized to a single transcript of nearly 6 kb in size. It is localized to the nucleus, specifically the nucleolus of cells. Extensive computer analysis was performed with the sequence of the full length NFBP and significant homology was found between NFBP, and yeast and mouse proteins. A discussion of the potential roles of NFBP in normal and viral infected cells is included.
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PMID:Identification of a novel protein from glial cells based on its ability to interact with NF-kappaB subunits. 1462 48

In HIV-1 infected cells, the LTR promoter, once organized into chromatin, is transcriptionally inactive in the absence of stimulation. To examine the chromosomal events involved in transcriptional activation, we analyzed histone acetylation and factor recruitment at contiguous LTR regions by a quantitative chromatin immunoprecipitation assay. In chronically infected cells treated with a phorbol ester, we found that acetylation of both histones H3 and H4 occurs at discrete nucleosomal regions before the onset of viral mRNA transcription. Concomitantly, we observed the recruitment of known cellular acetyl-transferases to the promoter, including CBP, P/CAF and GCN5, as well as that of the p65 subunit of NF-kappa B. The specific contribution of the viral Tat transactivator was assayed in cells harboring the sole LTR. We again observed nucleosomal acetylation and the recruitment of specific co-factors to the viral LTR upon activation by either recombinant Tat or a phorbol ester. Strikingly, P/CAF was found associated with the promoter only in response to Tat. Taken together, these results contribute to the elucidation of the molecular events underlying HIV-1 transcriptional activation.
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PMID:Regulation of HIV-1 gene expression by histone acetylation and factor recruitment at the LTR promoter. 1465 27


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