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)

The rev gene of human immunodeficiency virus type 1 (HIV-1) encodes a 116 amino acid nuclear regulatory protein (Rev) that increases the cytoplasmic expression of viral mRNAs containing the Rev response element (RRE) and coding for the structural proteins, Gag and Env. To identify the functional domains of Rev, amino acid deletion and chain termination mutations were introduced in the Rev coding region. The ability of these mutants to increase the cytoplasmic expression of a Rev-test plasmid (pSV-AR), containing the RRE cloned into the 3' noncoding region of the CAT gene in plasmid pSV2CAT, was examined in transient expression assays in HeLa cells. Our results indicate that three distinct regions mapping within the N-terminal 98 amino acids of Rev are essential for its activity. The subcellular localization of the various Rev proteins was examined in COS cells by indirect immunofluorescence. Rev was found to localize predominantly in the nucleolus of transfected cells. All mutant Rev proteins, with the exception of a deletion mutant (rev delta 41-44) lacking four Arg residues of a highly basic domain, were found to localize in the nucleolus. Mutant rev delta 41-44 exhibited weak diffuse fluorescence in the nucleus with a tendency to accumulate in the cytoplasm. A 15 amino acid region encompassing this basic domain (38-52) when fused to the Escherichia coli beta-galactosidase gene efficiently directed the fusion gene product to the nucleus and nucleolus, suggesting a role for this domain in the nucleolar localization of Rev.
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PMID:Functional domains of the HIV-1 rev gene required for trans-regulation and subcellular localization. 210 12

The envelope protein of the human T-cell leukemia virus type I (HTLV-I) is highly conserved among the isolates sequenced so far, as opposed to what is observed for the human immunodeficiency virus (HIV) envelope. By linker insertion scanning, we have produced 33 random mutations along the HTLV-I envelope gene, cloned into a eukaryotic expression vector. The resulting envelope products were analysed by immunoprecipitation and syncytia formation after transfection into COS-1 cells. We show here that 25 out of 33 mutations result in a non-functional envelope product as assessed by the lack of ability to form syncytia. In the majority of these mutants, the processing of the envelope gp61 precursor into the mature gp45 and gp20 proteins was affected. We propose that conformational constraints for processing and fusion abilities tend to limit the variability of the HTLV-I envelope. In three mutants, processing was observed but no syncytia were formed. These mutations might affect regions important for HTLV-I envelope functions, such as the receptor binding region.
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PMID:Mutations introduced along the HTLV-I envelope gene result in a non-functional protein: a basis for envelope conservation? 212 68

The coexpression of biologically active simian immunodeficiency virus (SIV) Rev and Env gene products was obtained in COS-1 cells from a single SIV subgenomic segment (which contains both exons of rev and the entire env gene) cloned into a SV40-directed vector. The SIVsm Rev trans-activated the expression of the full-length env mRNA and was required for the production of envelope glycoproteins. Furthermore, the alignment of the structural conservation of the Rev functional domains among all HIV and SIV was analyzed.
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PMID:Coexpression of biologically active simian immunodeficiency virus (SIV) Rev and Env in an SV40 system: the SIV rev gene regulates env expression. 216 37

Kaposi's sarcoma (KS) is frequently associated with human immunodeficiency virus-1 (HIV-1) infection. Supernatants from HIV-1-infected T cells carrying the CD4 antigen promote the growth of cells derived from KS lesions of AIDS patients (AIDS-KS cells), and the HIV-1 tat gene, introduced into the germ line of mice, induces skin lesions closely resembling KS. Here we report that the tat gene product (Tat) is released from both HIV-1-acutely infected H9 cells and tat-transfected COS-1 cells. These Tat-containing supernatants specifically promote growth of AIDS-KS cells which are inhibited by anti-Tat antibodies; recombinant Tat has the same growth-promoting properties. Therefore a viral regulatory gene product can be released as a biologically active protein and directly act as a growth stimulator. These and previous data indicate that extracellular Tat could be involved in the development or progression, or both, of KS in HIV-1-infected individuals.
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PMID:Tat protein of HIV-1 stimulates growth of cells derived from Kaposi's sarcoma lesions of AIDS patients. 218 72

Different chimeric antibody-like molecules consisting of the four human CD4 extracellular domains (amino acids 1-369) fused to different parts of human IgG1 and IgM heavy-chain constant regions have been created and expressed in mammalian cells. For both IgG1 and IgM fusion proteins, the best expression in COS cells was observed for molecules lacking the CH1 domain of the heavy-chain constant region. The chimeric molecules are potent inhibitors of human immunodeficiency virus (HIV) infection and HIV-mediated cytotoxicity. A CD4:IgG1 hinge fusion protein, which was analyzed in more detail, binds efficiently to HIV gp160 and human Fc receptors and shows complement-assisted inhibition of viral propagation in culture. Half-life studies after intravenous application of the latter human fusion protein into mice and monkeys showed significant prolongation of serum survival compared to soluble CD4. An IgG2b murine homolog of the human CD4:IgG1 hinge fusion protein was prepared and evaluated in mice, where it was found to be nontoxic and to have no detectable effect on the humoral response to soluble antigen.
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PMID:Expression and characterization of human CD4:immunoglobulin fusion proteins. 219 3

The expression of human immunodeficiency virus 1 (HIV-1) envelope glycoprotein products was studied in cells transfected with env gene constructs transcribed from an SV40 promoter. Gene constructs possessing the complete tat, rev (tat+ rev+) and env genes were transiently expressed in COS-1 cells as precursor SU-TM (gp160), SU.TM (gp120 x 41), and nucleolar rev protein. In addition, envelope glycoprotein was detected on the surface of those transfected COS-1 cells expressing abundant levels of env protein. Transfected constructs possessing a mutated tat translational initiation codon (tat-rev+) were expressed in COS-1 cells with at least a 10-fold increase in the level of envelope glycoprotein expression compared to the analogous constructs with an intact tat AUG codon (tat+ rev+). Mutation of the rev initiation codon (tat+ rev-) and (tat-rev-) resulted in no detectable expression of env products but expression of these proteins could be rescued by co-transfection of a cDNA encoding the rev gene. Subgenomic tat/rev transcripts were detected following transfection of all of the gene constructs indicating splicing of the env mRNAs transcribed from a heterologous promoter. Unspliced env transcripts were only detected in the cytoplasm of cells transfected with (rev+) constructs or with the (tat- rev-) construct in the presence of the rev cDNA supplied in trans. In contrast, unspliced transcripts were detected in the nuclear and total cellular RNA of all transfected cells. Expression of rev protein was localized to the nucleolus of transfected COS-1 cells. These results indicate that the export of unspliced env mRNA to the cytoplasm is facilitated by the expression of rev. Following env synthesis, the conversion of SU-TM (gp160) to SU.TM (gp120 x 41) was not quantitative. After a 20-h pulse-chase, only 40% of the SU-TM (gp160) present at the start of the chase period was subsequently accountable as mature SU (gp120), and approximately 30% of the detectable SU (gp120) was found in the culture medium of transfected COS-1 cells. The findings indicate that the surface expression of SU.TM (gp120 x 41) derived from heterologous gene transcripts is modulated (i) the co-expression of rev, (ii) the efficiency of proteolytic processing of SU-TM (gp160), and (iii) the degree of SU (gp120) shedding and/or secretion from the cell.
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PMID:Expression of human immunodeficiency virus 1 (HIV-1) envelope gene products transcribed from a heterologous promoter. Kinetics of HIV-1 envelope processing in transfected cells. 222 68

We have previously described the cloning and sequencing of a novel stain of human immunodeficiency virus type 2 (HIV-2) called HIV-2NIH-Z. A plasmid clone, pHIV2Z, containing the full-length provirus has now been constructed, and virus particles have been obtained upon transfection into COS-1 and H-9 cells. These particles can infect a number of T-cell lines and exert a cytopathic effect on fresh human and macaque peripheral blood lymphocytes. The cloned virus is biologically and morphologically indistinguishable from its parental uncloned strain as shown by restriction enzyme analysis, electron microscopy, and kinetics of infection. However, as shown by radioimmunoprecipitation assays, the cloned virus-infected cells express a full-length gp41 protein as predicted by the nucleotide sequence, whereas the wild-type parental strain expresses a truncated gp33 protein. Both the parental strain and the cloned virus possess a deletion encompassing the end of the nef gene within the U3 region which apparently does not affect their in vitro cytopathic and replicative capacities.
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PMID:In vitro characterization of a biologically active molecular clone of HIV-2NIH-Z containing a nef deletion and expressing a full-length transmembrane protein. 226 26

The tat protein of human immunodeficiency virus (HIV) has a characteristic cysteine-rich region containing 7 cysteines within 16 residues. The role of this region was investigated by creation of several tat gene mutants. The activities of the novel tat gene translational products were assayed by measuring the co-transfected chloramphenicol acetyl-transferase (CAT) gene expression controlled by HIV long-terminal repeat (LTR) in the COS 7 cells. Substitution of either Cys22 with Gly, or Cys34-Gln-Val-Cys with His-Gln-Val-His, and deletion behind Lys50 of the tat protein caused a drastic loss in its activity.
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PMID:Role of the cysteine-rich region of HIV tat protein on its trans-activational ability. 254 58

Three full-length cDNA clones were obtained from cells infected with the simian immunodeficiency virus (SIV) isolated from captive macaques (SIVMAC). Nucleotide sequence analyses suggested that these represented mRNA for the SIV MAC genes tat, rev (formerly, art/trs), and nef (formerly, 3'orf). The putative tat-specific clone was active in trans-activation of the SIV MAC long terminal repeat in COS-1 and Jurkat cells. In contrast, the human immunodeficiency virus 1 long terminal repeat was significantly trans-activated only in the COS-1 cells. This suggests that trans-activation by the SIV tat gene is modulated by cell-specific factors. The structure of all of the clones suggested an mRNA splicing pattern more complex than that described for human immunodeficiency virus 1.
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PMID:Structure of simian immunodeficiency virus regulatory genes. 254 74

It is generally believed that the gag gene product of human immunodeficiency virus type 1 (HIV-1) is processed into several core proteins by a virus-specific protease. We used deletion mutation analysis to study the role of HIV-specific protease in the processing of core proteins and its requirement for viral infectivity. Several mutant genomes with deletions in the protease gene were constructed. A mammalian cell line, COS-M6, transfected with the wild-type viral genome was shown to produce virions containing processed core proteins, while COS-M6 cells transfected with two mutated genomes could express only the core protein precursor, Pr56gag. The wild-type transfectant produced infectious virus; both transfectants expressing the mutated genomes also produced virions, and one of them still retained reverse transcriptase activity. However, the mutant viral particles were devoid of infectivity. Virions with a distinct central core and an electron-dense nucleoid budded out from the plasma membrane of COS-M6 cells transfected with the wild-type genome. In contrast, noninfectious virions that budded either into cytoplasmic vacuoles or out from the plasma membrane of COS-M6 cells transfected with mutant genomes contained ring-shaped nucleoids. These results indicate that the HIV-1 protease plays a role not only in the maturation of the core proteins but also in the assembly of the virus and thus is required for viral infectivity.
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PMID:Role of human immunodeficiency virus type 1-specific protease in core protein maturation and viral infectivity. 265 99


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