Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0019693 (HIV)
 170,526 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

We generated Chinese hamster ovary cell lines that stably express wild-type, secreted, and glycosylphosphatidylinositol (GPI)-anchored envelope glycoprotein of human immunodeficiency virus type 1 (HIV-1). The cells expressing wild-type Env (WT cells) express both the precursor gp160 and the mature gp120/gp41 and readily form large syncytia when cocultivated with CD4+ human cells. The cells expressing secreted Env (SEC cells) release 140-kDa precursor and mature 120-kDa envelope glycoproteins into the supernatants. The cells expressing GPI-anchored Env (PI cells) express both 140-kDa precursor and mature gp120/gp41 envelope glycoproteins, which can be released from the cell surface by treatment with phosphatidylinositol-specific phospholipase C (PI-PLC). Both the secreted and PI-PLC-released envelope glycoproteins form oligomers that can be detected on nonreducing sodium dodecyl sulfate-polyacrylamide gels. In contrast to the WT cells, the SEC and PI cells do not form syncytia when cocultivated with CD4+ human cells. The availability of cells producing water-soluble oligomers of HIV-1 Env should facilitate studies of envelope glycoprotein structure and function. The WT cells, which readily induce syncytia with CD4+ cells, provide a convenient system for assessing potential fusion inhibitors and for studying the fusion mechanism of the HIV Env glycoprotein.
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PMID:Characterization of stable Chinese hamster ovary cells expressing wild-type, secreted, and glycosylphosphatidylinositol-anchored human immunodeficiency virus type 1 envelope glycoprotein. 823 Apr 30

Tumor Necrosis Factor (TNF) is one of the most potent physiological inducers of the nuclear transcription factor NF-kappa B. In light of the pivotal role of NF-kappa B in the development of immune responses and activation of HIV replication, the identification of TNF signal transduction pathways involved in NF-kappa B activation is of particular interest. Data from our laboratory demonstrate that the TNF signal transduction pathway-mediating NF-kappa B activation involves two phospholipases, a phosphatidylcholine-specific phospholipase C (PC-PLC) and an endosomal acidic sphingomyelinase (aSMase). The aSMase activation by TNF is secondary to the generation of 1,2-diacylglycerol (DAG) produced by a TNF-responsive PC-PLC. SMase and its product ceramide induce degradation of the NF-kappa B inhibitor I kappa B as well as NF-kappa B activation. Besides endosomal acidic SMase, TNF also rapidly activates a plasmamembrane-associated neural SMase (nSMase), that, however is not involved in TNF-induced NF-kappa B activation. NSMase and aSMase are activated by different cytoplasmic domains of the 55 kDa TNF-receptor and are coupled to select pathways of TNF signaling. Ceramide generated by nSMase directs the activation of proline-directed serin/threonine protein kinases and phospholipase A2 and ceramide produced by aSMase triggers the activation of NF-kappa B. No apparent crosstalk was detected between nSMase and aSMase pathways, indicating that ceramide action depends on the topology of its production.
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PMID:TNF-induced activation of NF-kappa B. 853 Jan 43

The amounts of cell-surface glycosphingolipids and plasma membrane enzymes produced on the peripheral blood mononuclear cells (PBMNCs) isolated from 101 intravenous drug users (IDUs), of whom 91 were HIV-1 seropositive, were examined. Seronegative IDUs and age-matched healthy donors served as controls. The numbers of circulating CD3+, CD4+, and CD8+ T lymphocytes decreased during the advanced stages of the infection. There were also fewer CD4+ T-helper cells in HIV-1--seronegative IDU drug addicts. PBMNCs from HIV-1--seropositive subjects had abnormal surface enzyme kinetics. The phospholipase C had two pH optima, whereas the enzyme on normal cells has only one. The specific activity in cells from AIDS subjects was 4 times lower than that in normal PBMNCs. 5'-Nucleotidase showed a similar trend, whereas neutral endopeptidase activity did not correlate with the amounts of surface common acute lymphoblastic leukemia antigen (CALLA). These enzyme activities were decreased in HIV-seronegative IDUs. The subcellular distribution of enzymes and the profile of surface glycosphingolipids were also markedly changed, indicating the profound alterations in the membranes of PBMNCs from HIV-1--seropositive IDUs. These data suggest that intravenous drug use compromises the biochemical and structural integrity of the membrane surface of PBMNCs even before the onset of HIV.
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PMID:Changes in membrane enzymes and glycosphingolipids in lymphocytes from HIV-1--infected and noninfected intravenous drug users. 855 2

The 5'-upstream region of the rat phospholipase C-beta 3 gene (PLC-beta 3) has been cloned and characterized. Sequence analysis of the 5'-upstream region showed that it contains a GC-rich region (-166 to +1: 79%) and multiple binding sites for the transcription factors Sp1, AP-1 and AP-2, but does not contain a canonical TATA box. Primer extension analysis of total RNA isolated from rat glial cell C6Bul revealed that single transcription start point (tsp) is located at an initiator (Inr) element similar to that found in the HIV promoter. Gel mobility shift and competitive mobility shift assays indicated that this Inr element forms a DNA-protein complex with the HIV Inr-binding protein, LBP-1/CP2 or a homologue. In order to localize functional elements of the 5'-upstream region of the rat PLC-beta 3 gene, 5'-deletion fragments were cloned into a chloramphenicol acetyltransferase (CAT) reporter vector. Transient transfection analyses of the 5'-deletion mutants identified a crucial promoter element located at -128 to -14. Supershift mobility assays, site-directed mutagenesis and DNase I footprints indicated that Sp1 binds to three GC boxes within the sequence between -128 and -14 of the PLC-beta 3 promoter. Transient transfection analyses of promoter constructs containing site-specific mutation(s) of these three GC boxes demonstrated that two GC boxes, located proximal to the tsp, are important elements for normal promoter activity.
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PMID:The 5'-upstream region of the rat phospholipase C-beta 3 gene contains two critical Sp1 sites and an HIV Inr-like element. 933 46

Activation and infection by HIV-1 of glial cells and infiltrating macrophages are cardinal features of AIDS-related neurological disease. Tumor necrosis factor-alpha (TNF-alpha) is released by these cell types, and increased TNF-alpha mRNA and protein levels are associated with the development and severity of HIV-induced neurological disease. HIV-1 proteins have been implicated in HIV neuropathogenesis including Tat which has been shown to be a potent inducer of TNF-alpha. We review our data showing the induction of TNF-alpha by Tat in primary human fetal astrocytes, human peripheral blood mononuclear cells, macrophages, and astrocytic and macrophage cell lines. TNF-alpha induction was NF-kappaB dependent and was eliminated by inhibiting protein kinase A, phospholipase C and protein tyrosine kinase activity. In addition, we examined the molecular diversity of the tat genome in the brains of HIV-infected patients from different HIV-1 clades. Comparison of matched brain- and spleen-derived tat sequences indicated that homology among brain-derived clones was greater than that between the brain- and spleen-derived clones. The brain-derived tat sequences were markedly heterogeneous in regions which influence viral replication and intracellular transport. Future studies using Tat, encoded by different sequences, will be necessary to determine the functional significance of tat molecular diversity. Nonetheless, these studies suggest that Tat is an important inducer of TNF-alpha production and thus may play a key role in the pathogenesis of HIV-related neurological disease.
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PMID:HIV-1 tat molecular diversity and induction of TNF-alpha: implications for HIV-induced neurological disease. 973 Jun 85

Aerolysin is a channel-forming toxin secreted by Aeromonas spp. that binds to glycosyl phosphatidylinositol (GPI)-anchored proteins, such as Thy-1, on sensitive target cells. Receptor binding is followed first by oligomerization of the toxin and then by insertion of the oligomers into the membrane to form stable channels that disrupt the permeability barrier. Human immunodeficiency virus type 1 (HIV-1) produced from T cells is known to incorporate Thy-1 and other GPI-anchored proteins into its membrane. Here, we show that aerolysin is capable of neutralizing HIV-1 in a dose-dependent manner and that neutralization depends upon the presence of these proteins in the viral envelope. Pretreatment with phosphatidylinositol-specific phospholipase C to remove GPI-anchored proteins greatly reduced HIV-1 sensitivity to the toxin, and virus originating from a mutant cell line that lacks GPI-anchored proteins was not neutralized. Aerolysin variants with single amino acid changes that prevent oligomerization or insertion of the toxin were unable to inactivate the virus, implying that channel formation is necessary for neutralization to occur. These findings represent the first evidence that a pathogenic human virus can be neutralized by a bacterial toxin.
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PMID:The channel-forming toxin aerolysin neutralizes human immunodeficiency virus type 1. 1041 55

HIV-1 infection commonly leads to neuronal cell death and a debilitating syndrome known as AIDS-related dementia complex. The HIV-1 protein Tat is neurotoxic, and because cell survival is affected by the intracellular calcium concentration ([Ca2+]i), we determined mechanisms by which Tat increased [Ca2+]i and the involvement of these mechanisms in Tat-induced neurotoxicity. Tat increased [Ca2+]i dose-dependently in cultured human fetal neurons and astrocytes. In neurons, but not astrocytes, we observed biphasic increases of [Ca2+]i. Initial transient increases were larger in astrocytes than in neurons and in both cell types were significantly attenuated by antagonists of inositol 1,4,5-trisphosphate (IP3)-mediated intracellular calcium release [8-(diethylamino)octyl-3,4,5-trimethoxybenzoate HCI (TMB-8) and xestospongin], an inhibitor of receptor-Gi protein coupling (pertussis toxin), and a phospholipase C inhibitor (neomycin). Tat significantly increased levels of IP3 threefold. Secondary increases of neuronal [Ca2+]i in neurons were delayed and progressive as a result of excessive calcium influx and were inhibited by the glutamate receptor antagonists ketamine, MK-801, (+/-)-2-amino-5-phosphonopentanoic acid, and 6,7-dinitroquinoxaline-2,3-dione. Secondary increases of [Ca2+]i did not occur when initial increases of [Ca2+]i were prevented with TMB-8, xestospongin, pertussis toxin, or neomycin, and these inhibitors as well as thapsigargin inhibited Tat-induced neurotoxicity. These results suggest that Tat, via pertussis toxin-sensitive phospholipase C activity, induces calcium release from IP3-sensitive intracellular stores, which leads to glutamate receptor-mediated calcium influx, dysregulation of [Ca2+]i, and Tat-induced neurotoxicity.
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PMID:Involvement of inositol 1,4,5-trisphosphate-regulated stores of intracellular calcium in calcium dysregulation and neuron cell death caused by HIV-1 protein tat. 1050 Nov 79

Most human lymphomas remain heterogeneous biologic entities in spite of recent advances in the description of their clinical presentation, cellular morphology, immunophenotype, and genotype. Elucidation of genetic alterations causing malignant transformation may explain pathogenesis, refine differential diagnosis, clarify prognosis, and provide rational basis for new therapy. During the last year the expression of anaplastic lymphoma kinase clarified presentation and provided clues toward the outcome of anaplastic large cell lymphoma; the breakpoints of t(2;5) were mapped; constitutive activation of anaplastic lymphoma kinase by a chromosomal inversion was described; transformation was shown to be independent of nuclear localization of anaplastic lymphoma kinase; and phospholipase C-gamma was identified as a molecular target for the kinase activity of anaplastic lymphoma kinase. Molecular characterization of recurrent chromosome abnormalities has identified new candidate oncogenes: bcl-9, bcl-10, PAX-5, MMSET, and c-maf. Their precise role in malignant transformation, and the frequency of their alteration in lymphoma and myeloma, is not yet defined. The expression of the antiapoptotic protein bcl-2 on aggressive lymphomas was shown to be associated with inferior disease-free survival by several investigators. This may be a target of pharmacologic reduction of bcl-2 levels. Can these advances in molecular pathogenesis improve cure rates for lymphoma? The spectacularly successful molecular modeling of inhibitors for HIV protease suggests that this may be an attainable objective.
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PMID:Recent advances in the molecular pathogenesis of lymphomas. 1050 66

Local TNF-alpha production in different organs may affect HIV replication and pathogenesis. Alveolar macrophages (AMs) obtained by bronchoalveolar lavage from asymptomatic HIV-seropositive and HIV-seronegative individuals did not spontaneously release TNF-alpha, but LPS stimulation of these cells significantly increased TNF-alpha production. We tested whether NF-kappa B affects TNF-alpha production by AMs using N-tosyl-<cmd SC>l<cmd /SC> -phenylalanine chloromethylketone (TPCK) or N-benzoyl-<cmd SC>l<cmd /SC> -tyrosine ethyl ester (BTEE), which inhibit the degradation of I kappa B, or tricyclodecan-9-yl-xanthogenate-potassium (D609), which inhibits phospholipase C. Alveolar macrophages were exposed to LPS alone and with the chemical protease inhibitors TPCK, BTEE, and D609. NF-kappa B DNA binding induced by LPS treatment of AMs was inhibited by TPCK, BTEE, and D609. These agents also inhibited TNF-alpha mRNA and TNF-alpha protein production. After 24 h, the levels of TNF-alpha mRNA reached equilibrium, as assessed by RT-PCR. The levels of NF-kappa B mRNA remained constant under all conditions. The levels of I kappa B-alpha mRNA were similar after 30, 60, and 180 min, but the I kappa B-beta mRNA concentration was initially low and increased over time under all conditions. I kappa B-alpha and I kappa B-beta protein production was not affected by the chemical protease inhibitors. Our data show that TNF-alpha production by LPS-stimulated AMs from asymptomatic HIV-seropositive and -seronegative individuals is regulated via the phospholipase C pathway and by NF-kappa B DNA binding activity without obvious changes in I kappa B-alpha or I kappa B-beta protein concentrations.
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PMID:NF-kappa B modulates TNF-alpha production by alveolar macrophages in asymptomatic HIV-seropositive individuals. 1064 Jul 79

HIV-1 protein Tat is neurotoxic and increases macrophage and microglia production of TNF-alpha, a cytopathic cytokine linked to the neuropathogenesis of HIV dementia. Others have shown that intracellular calcium regulates TNF-alpha production in macrophages, and we have shown that Tat releases calcium from inositol 1,4, 5-trisphosphate (IP3) receptor-regulated stores in neurons and astrocytes. Accordingly, we tested the hypothesis that Tat-induced TNF-alpha production was dependent on the release of intracellular calcium from IP3-regulated calcium stores in primary macrophages. We found that Tat transiently and dose-dependently increased levels of intracellular calcium and that this increase was blocked by xestospongin C, pertussis toxin, and by phospholipase C and type 1 protein kinase C inhibitors but not by protein kinase A or phospholipase A2 inhibitors. Xestospongin C, BAPTA-AM, U73122, and bisindolylmalemide significantly inhibited Tat-induced TNF-alpha production. These results demonstrate that in macrophages, Tat-induced release of calcium from IP3-sensitive intracellular stores and activation of nonconventional PKC isoforms play an important role in Tat-induced TNF-alpha production.
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PMID:Release of calcium from inositol 1,4,5-trisphosphate receptor-regulated stores by HIV-1 Tat regulates TNF-alpha production in human macrophages. 1084 12


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