Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0021051 (immunodeficiency)
 71,517 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Human immunodeficiency virus (HIV) is the cause of acquired immunodeficiency syndrome (AIDS). Encoded by the HIV genome are several precursor proteins that undergo proteolytic cleavage to yield functional proteins. The env precursor protein is cleaved by a cellular protease. The gag precursor protein of HIV (p55), however, is cleaved by a virally encoded aspartate protease (HIV Protease). Cleavage of p55 is required for viral maturation and infectivity. There are also several host cell aspartate proteases that serve important homeostatic functions. Cathepsins D and E are lysosomal aspartate proteases which are believed to play an important role in macrophage function, and it has been suggested that inhibition of these enzymes by an HIV protease inhibitor may exacerbate immunosuppression in AIDS patients. We have studied the effect of SK&F 107461 (a hydroxyethylene dipeptide isostere inhibitor of HIV protease), on various host defense functions of human monocytes. Pepstatin A (an inhibitor of most aspartate proteases) and leupeptin (an inhibitor of serine and cysteine proteases) were included as controls. Although less potent than the prototypic aspartate protease inhibitor pepstatin, SK&F 107461 inhibited partially purified cathepsin D in vitro. However, in cell-based assays, SK&F 107461 had no effect on the degradation of hemoglobin, antigen processing of the protein antigen streptokinase, or secretion of 17-kD IL-1 beta by monocytes at concentrations which inhibit maturation of intracellular virus in HIV infected monocytes. Furthermore, SK&F 107461 had no effect on constitutive candidacidal activity. In contrast, leupeptin and pepstatin A partially inhibited accessory cell function of monocytes in the proliferative response to the recall antigen streptokinase. In addition, leupeptin partially inhibited degradation of hemoglobin.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Effect of a human immunodeficiency virus protease inhibitor on human monocyte function. 149 45

Transcription from the human immunodeficiency virus type 1 (HIV-1) provirus is activated by a cellular factor, NF kappa B, recognizing the tandemly repeated 10-base-pair sequences, termed the kappa B sequence, present in the enhancer region within the viral long terminal repeat (LTR). Using electrophoretic mobility shift assay (EMSA), which demonstrates specific DNA-protein interaction in vitro, we could demonstrate that reducto-oxidative modulation of NF kappa B dramatically changes its DNA binding activity and that a cellular physiological reducing catalyst, thioredoxin (TRX) also known as adult T cell leukemia derived factor (ADF), fully restored the DNA-binding activity of the oxidized NF kappa B. We also observed that purified TRX/ADF protein could augment gene expression from HIV LTR as demonstrated by transient chloramphenicol acetyltransferase (CAT) assay. These observations confirmed the previous notion that ADF might be an inducing factor of cellular interleukin-2 receptor alpha subunit (IL-2R alpha) through the kappa B sequence that is a common central cis-regulatory element in both IL-2R alpha and HIV gene expression. These observations indicate that reducto-oxidative regulation (or redox regulation) of a cysteine residue(s) on the NF kappa B molecule might play an important role in its specific DNA interaction and that it might provide a clue to the understanding of a pathway of cellular signal transduction to NF kappa B that is independent from the known pathways involving protein phosphorylation.
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PMID:Human thioredoxin/adult T cell leukemia-derived factor activates the enhancer binding protein of human immunodeficiency virus type 1 by thiol redox control mechanism. 149 89

The ability of the human immunodeficiency virus (HIV) to replicate in CD+ T lymphocytes and mononuclear phagocytes(MP) is strongly influenced by immunoregulatory cytokines. In the T cell system, interleukin-2 (IL-2) provides a mitogenic signal leading to both cell proliferation and virus replication. Among other HIV-inductive cytokines, only tumor necrosis factor-alpha or -beta (TNF-alpha/-beta) have been shown thus far to trigger virus expression both in T cells and MP. The mechanism of action of TNF involves the activation of the cellular transcription factor NF-kB which binds to specific consensus sequences present in the enhancer region of the HIV proviral LTR. In addition, several other cytokines (including colony stimulating factors, IL-1, IL-3, and IL-6) have demonstrated upregulatory effects on HIV production in MP, whereas nonimmune interferons (INF-alpha/-beta) have been shown to suppress HIV replication in T cells and MP by acting at different phases in the virus life cycle. Finally, cytokines such as TGF-beta, IFN-gamma, and IL-4 have demonstrated either upregulatory or suppressive effects on virus expression depending on the experimental conditions. This scenario indicates that HIV expression is under the control of a complex network of immunoregulatory cytokines, in addition to its own endogenous regulatory proteins, suggesting that new pharmacologic strategies may be aimed at either mimicking or interrupting cytokine-dependent virus expression. In this regard, a number of different physiologic and pharmacologic agents capable of interfering with cytokine-mediated events, including glucocorticoids, anti-oxidants, such as N-Acetyl-L-Cysteine (NAC), and retinoic acid (RA) have already been shown to profoundly affect HIV replication in vitro.
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PMID:The effect of cytokines and pharmacologic agents on chronic HIV infection. 154 Apr 7

Several investigators have implicated depletion of glutathione (GSH) and production of reactive oxygen intermediates (ROIs) in the regulation of the human immunodeficiency virus (HIV). We have shown directly that N-acetylcysteine (NAC) blocks HIV expression in chronic and acute infection models, and HIV replication in normal peripheral blood mononuclear cells. NAC is a cysteine prodrug which maintains intracellular thiol levels during oxidative stress and replenishes depleted GSH. The observed antiviral effect of NAC is due to inhibition of viral stimulation by ROIs, which are produced in response to inflammatory cytokines. We have also shown that HIV-infected individuals have decreased intracellular GSH levels in their circulating T cells. Since GSH is the major protection against the production of ROIs, we hypothesize that the observed decrease is due to a chronic oxidative stress induced by continual exposure to elevated levels of inflammatory cytokines. Together, these results provide a rationale for clinical trials testing the efficacy of GSH-replenishing drugs such as NAC in the treatment of AIDS. NAC is different than many other antiviral drugs in that it inhibits host-mediated stimulation of viral replication arising in normal immune responses, and may thereby extend latency. In addition, it inhibits the action of inflammatory cytokines which may mediate cachexia, thereby raising the possibility that it may alleviate the deleterious wasting that accompanies late stage AIDS.
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PMID:N-acetylcysteine: a new approach to anti-HIV therapy. 154 Apr 8

The third variable (V3) domain has been implicated in determining the human immunodeficiency virus (HIV) phenotype, including fusion capacity and monocytotropism. In a large set of primary HIV type 1 (HIV-1) isolates, V3 sequence analysis revealed that fast-replicating, syncytium-inducing isolates contained V3 sequences with a significantly higher positive charge than those of slow-replicating, non-syncytium-inducing monocytotropic isolates. It appeared that these differences in charge could be attributed to highly variable amino acid residues located on either side of the V3 loop, midway between the cysteine residues and the central GPG motif. In non-syncytium-inducing monocytotropic isolates, these residues were negatively charged or uncharged, whereas in syncytium-inducing nonmonocytotropic isolates, either one or both were positively charged. The substitutions at these positions result in changes in the predicted secondary structure of the V3 loop. Our data suggest that two amino acid residues in the highly variable V3 domain are responsible for phenotype differences and point to conformational differences in V3 loops from phenotypically distinct HIV-1 isolates.
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PMID:Phenotype-associated sequence variation in the third variable domain of the human immunodeficiency virus type 1 gp120 molecule. 156 May 43

tat, an essential transactivator of gene transcription in the human immunodeficiency virus (HIV), is believed to activate viral gene expression by binding to the transactivation response (TAR) site located at the 5' end of all viral mRNAs. The TAR element forms a stem-loop structure containing a 3-nucleotide bulge that is the site for tat binding and is required for transactivation. Here we report the synthesis of a site-specific chemical ribonuclease based on the TAR binding domain of the HIV type 1 (HIV-1) tat. A peptide consisting of this 24-amino acid domain plus an additional C-terminal cysteine residue was chemically synthesized and covalently linked to 1,10-phenanthroline at the cysteine residue. The modified peptide binds to TAR sequences of both HIV-1 and HIV-2 and, in the presence of cupric ions and a reducing agent, cleaves these RNAs at specific sites. Cleavage sites on TAR sequences are consistent with peptide binding to the 3-nucleotide bulge, and the relative displacement of cleavage sites on the two strands suggests peptide binding to the major groove of the RNA. These results and existing evidence of the rapid cellular uptake of tat-derived peptides suggest that chemical nucleases based on tat may be useful for inactivating HIV mRNA in vivo.
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PMID:Site-specific cleavage of the transactivation response site of human immunodeficiency virus RNA with a tat-based chemical nuclease. 156 48

The v- and c-Rel oncoproteins bind to oligonucleotides containing kappa B motifs, form heterodimers with other members of the Rel family, and modulate expression of genes linked to kappa B motifs. Here, we report that the RxxRxRxxC motif conserved in all Rel/kappa B family proteins is absolutely required for v-Rel protein-DNA contact and its resulting transforming activity. We also demonstrate that serine substitution of the cysteine residue conserved within this motif enables v-Rel to escape redox control, thereby promoting overall DNA binding. These mutant proteins retained the ability to competitively inhibit kappa B-mediated transcriptional activation of the human immunodeficiency virus long terminal repeat but failed to efficiently transform chicken lymphoid cells both in vitro and in vivo. Our data indicate that reduction of the conserved cysteine residue in the RxxRxRxxC motif may be required for optimal DNA-protein interactions. These results provide direct biochemical evidence that the DNA-binding activity of v-Rel is subject to redox control and that the conserved cysteine residue in the RxxRxRxxC motif is critical for this regulation. These studies suggest that the DNA-binding, transcriptional, and biological activities of Rel family proteins may also be subject to redox control in vivo.
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PMID:The RxxRxRxxC motif conserved in all Rel/kappa B proteins is essential for the DNA-binding activity and redox regulation of the v-Rel oncoprotein. 162 Jan 18

Using a transient expression assay in Vero cells, we have shown that the protein product from gene 61 of varicella-zoster virus (VZV) can repress the function of the VZV encoded trans-activators on putative viral immediate-early, early, and late gene promoters. The repression is exerted at the transcriptional level and requires functional gene 61 protein. This trans-repressor is the herpes simplex type 1 ICP0 (a trans-activator) homolog, as defined by gene location, the sharing of a cysteine-rich putative zinc-binding finger in the amino-terminal region, and limited amino acid homology. Open reading frame 61 (ORF61)-mediated trans-repression appears to be specific for VZV-encoded trans-activators in that it has no effect on simian virus 40 and Rous sarcoma virus promoters. Moreover, it does not inhibit trans-activation of the human T-lymphotropic virus type I and human immunodeficiency virus long terminal repeats by tax and tat genes, respectively. We constructed plasmids with mutations in ORF61 and tested them for their ability to inhibit trans-activator (VZV genes 4 and 62)-mediated activation of the viral thymidine kinase promoter-chloramphenicol acetyltransferase construct. Mutants containing interruptions in ORF61 lost their trans-repressing ability, as demonstrated at both the protein and steady-state RNA levels. These results suggest that the ORF61 protein product can mediate down-regulation of VZV gene expression.
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PMID:Characterization of a potent varicella-zoster virus-encoded trans-repressor. 165 42

The proteolytic processing pathway of the nucleocapsid protein (NC) by the viral proteinase within intact capsids of equine infectious anemia virus (EIAV) is presented. The cleavage sites are located at the carboxyl side of the first cysteine residue within the zinc-finger domains. EIAV is used as a model to predict similar NC cleavages in other retroviruses, including human immunodeficiency virus (HIV). The observed cleavages suggest a previously unrecognized function of the retroviral proteinase that may be crucial for replication during the early stages of the virus life-cycle (i.e. reverse transcription/integration).
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PMID:In situ processing of a retroviral nucleocapsid protein by the viral proteinase. 165 77

The nucleotide sequences of the envelope (env) coding regions of two strains of the feline immunodeficiency virus isolated in Zurich, Switzerland (FIVZ1, FIVZ2) have been analysed. In addition, the complete sequence of the FIVZ1 isolate has been determined. Comparisons have been made with the previously published sequences of three North American isolates (PPR and the Petaluma strains FIV34TF10 and FIV14). The isolate FIVZ1 was very similar to the Petaluma strains of FIV and may represent a clonal derivative acquired by 'contamination'. Overall there are between 2.6% and 15.1% amino acid changes in the env gene products of the five isolates. Of the Zurich isolates, FIVZ2 exhibited the greatest divergence to the other viruses and based on its genotype, phenotype and origins probably represents a new isolate of FIV. Possibly the viruses diverged only recently from a common ancestor. Some 31 of the 33 cysteine residues and 17 of the 21 potential N-linked glycosylation sites of the FIV34TF10 env gene product were conserved among all five isolates. The open reading frame 3 (ORF3, or D) which overlaps the env gene (but is encoded in a different frame) has an ATG codon downstream of a potential splice acceptor site in all five isolates, supporting the view that it encodes a viral gene product. In ORF3 of FIVZ1 a stop codon was located 16 amino acids upstream of the stop codon of ORF3 of the other isolates. The ORF4 (or G) of isolate FIVZ2, thought to be the second coding exon of an FIV rev-like gene, contained a nucleotide deletion in amino acid 45 of ORF4, resulting in a--1 frameshift at this position. Comparison of the LTR sequences of the five isolates identified conserved promoter/enhancer elements. A potential stem-loop structure was identified in the R region of the LTRs of all the isolates, despite the heterogeneity of nucleotide sequences in that region. Such structures (TAR) are present in analogous regions of other lentiviruses and are responsible for tat-mediated trans-activation.
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PMID:Identification of conserved and variable regions in the envelope glycoprotein sequences of two feline immunodeficiency viruses isolated in Zurich, Switzerland. 166 Feb 15


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