Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: DrugBank:EXPT01586 (G418)
 2,237 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

We have developed a vector (pSupexp), for high-level expression of genes, that is dependent on transactivation of the human immunodeficiency virus 1 (HIV-1) long terminal repeat (LTR) by the HIV-1 transactivator protein, Tat. The foreign gene, expressed under transcriptional control of the HIV-1 LTR, and the tat gene, expressed under transcriptional control of SV40 early promoter, are expressed from the same plasmid. The vector also has the neomycin resistance-encoding gene (neo), with G418 being used as a dominant selection marker for stable expression. We have cloned the bacterial cat gene into pSupexp and measured transient CAT production in human HeLa and A549 cells. Our results indicate that pSupexpCAT expresses about 25- to 68-fold higher levels of CAT activity as compared to other standard SV40- and Rous sarcoma virus-based vectors, and three- to fivefold more activity than the cytomegalovirus-based vector. Immunoprecipitation of the CAT protein also revealed a high level of production in human cells.
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PMID:A high-level expression vector for human cells. 139 42

The bacterial neomycin phosphotransferase gene driven by the Moloney mouse leukemia virus long terminal repeat (LTR) or SV40 early region promoter was introduced into the human promonocyte-macrophage cell line, U937, and into the pluripotential human embryonic teratocarcinoma cell line, NT2/D1. Clonally derived cell lines capable of growing in 2-4 mg/ml of the aminoglycoside antibiotic, G418 (Geneticin), were established and transfected with pHIVCat, a plasmid expressing the bacterial chloramphenicol acetyl transferase (CAT) activity under the control of the human immunodeficiency virus (HIV-1) LTR. All of the G418 resistant (neo(r)) U937 cell lines and 10 of 14 neo(r) NT2/D1 cell lines exhibited reduced basal levels of CAT expression or impaired responses to activation of the HIV-1 LTR by phorbol 12-myristate 13-acetate (PMA) when compared to the parental lines. Other differences included inhibition of tat activation of the HIV-1 LTR and increased sensitivity of U937 cells to human tumor necrosis factor alpha. The expression of other eukaryotic promoters including the HTLV-1 LTR, SV40 ori sequences, and the human beta-actin gene promoter was similarly affected. However, differentiation of the neo(r) U937 cells into macrophages was neither delayed nor impaired. Because PMA is an activator of protein kinase C (PKC) and a potent inducer of HIV-1 directed gene expression, the amounts, sensitivity to G418, and cytosol to membrane translocation of this enzyme were determined in the wild type and neo(r) U937 cells. G418 at concentrations too low to affect cell growth (12-150 micrograms/ml) inhibited PMA-induced transactivation responses in wild type cells but did not inhibit PKC-dependent protein phosphorylation in vitro. PKC activities in the wild type and neo(r) cells were similar in absolute amounts and in the cytosol-membrane distribution of the enzyme. In contrast with wild type cells, however, all of the cytosolic Ca(2+)-phospholipid-dependent form of PKC disappeared from the neo(r) cells within 30 min after PMA induction. The results suggested that, depending upon the cell type, gene cotransfer using aminoglycoside resistance as a selectable marker may seriously perturb important cellular control mechanisms such as the PKC pathway leading to activation of gene expression.
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PMID:Gene activation mediated by protein kinase C in human macrophage and teratocarcinoma cells expressing aminoglycoside phosphotransferase activity. 166 Apr 86

Human peripheral blood lymphocytes (PBLs) were transduced with a number of recombinant retroviruses including RRz2, an LNL6-based virus with a ribozyme targeted to the human immunodeficiency virus (HIV) tat gene transcript inserted within the 3' region of the neomycin-resistance gene; RASH5, and LNHL-based virus containing an antisense sequence to the 5' leader region of HIV-1 downstream of the human cytomegalovirus promoter; and R20TAR, an LXSN-based virus with 20 tandem copies of the HIV-1 trans-activation response element sequence driven by the Moloney murine leukemia virus long terminal repeat. After G418 selection, transduced PBLs were challenged with the HIV-1 laboratory strain IIIB and a primary clinical isolate of HIV-1, 82H. Results showed that PBLs from different donors could be transduced and that this conferred resistance to HIV-1 infection. For each of the constructs, a reduction of approximately 70% in p24 antigen level relative to the corresponding control-vector-transduced PBLs was observed. Molecular analyses showed constitutive expression of all the transduced genes from the retroviral long terminal repeat, but no detectable transcript was seen from the internal human cytomegalovirus transcript was seen from the internal human cytomegalovirus promoter for the antisense construct. Transduction of, and consequent transgene expression in, PBLs did not impact on the surface expression of either CD4+/CD8+ (measured by flow cytometry) or on cell doubling time (examined by [3H]thymidine uptake). These results indicate the potential utility of these anti-HIV-1 gene therapeutic agents and show the preclinical value of this PBL assay system.
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PMID:Resistance to human immunodeficiency virus type 1 infection conferred by transduction of human peripheral blood lymphocytes with ribozyme, antisense, or polymeric trans-activation response element constructs. 763 80

Inhibition of human immunodeficiency virus type 1 (HIV-1) replication was demonstrated by using tat- and rev-directed antisense oligoribonucleotides 68 and 69 nucleotides in length. In this study, human T-lymphoid cells were transduced with a murine amphotropic retroviral vector containing a polymerase III-driven chimeric gene consisting of the human tRNA(imet) sequence and the short tat- and rev-directed antisense sequences that had been shown before to inhibit HIV-1 replication. Pools of transduced, G418-resistant human T-lymphoid Jurkat or CEM cells showed reduced replication of HIV-1 in the presence of antisense-containing chimeric transcripts, but not with sense sequence-containing transcripts. These results demonstrate that short inhibitory antisense RNA transcripts can be stably expressed endogenously using polymerase III promoters, which can reduce replication of HIV-1. The approach described in this work combines the advantages of short and, usually, synthetic oligonucleotides with the stable intracellular expression of inhibitory genes for HIV-1 in target cells. Considering the small size of the described chimeric polymerase III genes, it appears feasible to combine multiple antiviral genes with the currently available retroviral vectors as gene delivery systems.
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PMID:Reduction in replication of the human immunodeficiency virus type 1 in human T cell lines by polymerase III-driven transcription of chimeric tRNA-antisense RNA genes. 784 87

The RAW264 murine macrophage cell line was used as a model to examine the role of the tat and nef gene products in the transcription regulation of the human immunodeficiency virus type 1 (HIV-1) long terminal repeat (LTR) in macrophages. Contrary to claims that the activity of the HIV-1 LTR responds poorly in rodent cells to trans activation by the viral tat gene product, cotransfection of RAW264 cells with a tat expression plasmid in transient transfection assays caused a > 20-fold increase in reporter gene expression that was inhibited by mutations in the TAR region. RAW264 cells stably transfected with the tat plasmid displayed similarly elevated HIV-1 LTR-driven reporter gene activity. By contrast to previous reports indicating a negative role for nef in HIV transcription, cotransfection of RAW264 cells with a nef expression plasmid trans activated the HIV-1 LTR driving either a chloramphenicol acetyltransferase or a luciferase reporter gene. The action of nef was specific to the LTR, as expression of nef had no effect on the activity of the simian virus 40, c-fms, urokinase plasminogen activator, or type 5 acid phosphatase promoter. trans-activating activity was also manifested by a frameshift mutant expressing only the first 35 amino acids of the protein. The effects of nef were multiplicative with those of tat gene product and occurred even in the presence of bacterial lipopolysaccharide, which itself activated LTR-directed transcription. Examination of the effects of selected mutations in the LTR revealed that neither the kappa B sites in the direct repeat enhancer nor the TAR region was required as a cis-acting element in nef action. The action of nef was not species restricted; it was able to trans activate in the human monocyte-like cell line Mono Mac 6. The presence of a nef expression cassette in a neomycin phosphotransferase gene expression plasmid greatly reduced the number of G418-resistant colonies generated in stable transfection of RAW264 cells, and many of the colonies that were formed exhibited very slow growth. The frameshift mutant was also active in reducing colony generation. Given the absence of any effect of the frameshift mutation on nef function, its actions on macrophage growth and HIV transcription are discussed in terms of the role of the N-terminal 30 amino acids and of stable secondary structures in the mRNA.
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PMID:Effects of the tat and nef gene products of human immunodeficiency virus type 1 (HIV-1) on transcription controlled by the HIV-1 long terminal repeat and on cell growth in macrophages. 823 Apr 18

Transfer of "anti-HIV-1 genes" into hematopoietic stem cells of human immunodeficiency virus-1 (HIV-1)-infected individuals may be a potent therapeutic approach to render mature cells arising from transduced stem cells resistant to the destructive events associated with HIV-1 infection. To determine the feasibility of gene therapy for acquired immunodeficiency syndrome in individuals already infected with HIV-1, granulocyte colony-stimulating factor mobilized peripheral blood CD34+ cells were isolated from HIV-1-infected individuals and transduced with retroviral vectors containing three different anti-HIV-1-genes: the Rev binding domain of the Rev Responsive Element (RRE decoy) (L-RRE-neo), a double hammerhead ribozyme vector targeted to cleave the tat and rev transcripts (L-TR/TAT-neo), and the trans-dominant mutant of rev (M10) (L-M10-SN). As a control, a vector mediating only neomycin resistance (LN) was used. After 3 days of transduction on allogeneic stroma in the presence of stem cell factor, interleukin-6 (IL-6), and IL-3, the cultures were G418-selected, and then challenged with HIV-1(JR-FL) and a primary HIV-1 isolate. Compared with the control cultures, the L-RRE-neo-, L-TR/TAT-neo-, and L-M10-SN-transduced cultures displayed up to 1,000-fold inhibition of HIV-1 replication after challenge with HIV-1(JR-FL) and the primary HIV-1 isolate. Growth of the hematopoietic cells in long-term bone marrow culture was not perturbed by the presence of any of the anti-HIV-1 genes. This study shows that anti-HIV-1 genes can be introduced into CD34+ cells from individuals already infected with HIV-1, and strongly inhibit HIV-1 replication in primary monocytes derived from the CD34+ progenitors.
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PMID:Inhibition of human immunodeficiency virus-1 (HIV-1) replication after transduction of granulocyte colony-stimulating factor-mobilized CD34+ cells from HIV-1-infected donors using retroviral vectors containing anti-HIV-1 genes. 911 67

Among potential genetic targets for intervention in the HIV-1 life cycle, the tat gene product is a key target. We investigated the ability of an antitat gene to inhibit HIV-1 activation and replication in chronically infected promonocyte (U1) and T cell (ACH-2) lines in vitro. U1 and ACH-2 cells were transduced with an antitat gene expressing RNA with dual (polymeric Tat activation response element and antisense-tat) function that interferes with HIV-1 replication. Tumor necrosis factor-alpha (TNF-alpha) plus phorbol 12- myristate 13-acetate (PMA)-induced HIV-1 expression, as determined by reverse transcribed PCR and reverse transcriptase (RT) assays, was significantly inhibited in U1 and ACH-2 cells transduced with the antitat gene, compared with the cells transduced with control vector and untransduced cells. This resistance to TNF-alpha plus PMA-induced HIV-1 expression was demonstrated in antitat gene-transduced U1 and ACH-2 cells maintained in G418-free media for 5 months, suggesting that functional antitat gene may persist for many months in transduced cells and their progeny. Most importantly, we demonstrate that the antitat gene, when introduced into peripheral blood mononuclear cells (PBMC) isolated from patients with HIV-1 infection, inhibited TNF-alpha plus PMA-induced viral replication as determined by RT-PCR and RT activity. In addition, the antitat gene enhanced the survival of CD4+ T lymphocytes from such patients. These data suggest the feasibility of utilizing antitat gene therapy to block activation and replication of HIV-1 in latently infected monocytes and T- lymphocytes in vivo. Gene Therapy (2000) 7, 321-328.
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PMID:Inhibition of HIV-1 replication in chronically infected cell lines and peripheral blood mononuclear cells by retrovirus-mediated antitat gene transfer. 1069 13

The small-ruminant lentiviruses ovine maedi-visna virus (MVV) and caprine arthritis-encephalitis virus (CAEV) cause encephalitis, progressive pneumonia, arthritis, and mastitis in sheep and goats. Icelandic MVV strains, which are lytic in tissue culture, have a wide species distribution of functional receptors, which includes human cells. In contrast, functional receptors for the nonlytic CAEV CO are absent from human cells. To determine if the wide species distribution of functional receptors is a common property of MVV strains or related to cytopathic phenotype, we tested the infectivity of viruses pseudotyped with the envelope glycoproteins of MVV K1514, CAEV CO, and lytic and nonlytic North American MVV strains to cells of different species. Replication-defective CAEV proviral constructs lacking the env, tat, and vif genes and carrying the neomycin phosphotransferase gene in the vif-tat region were developed for the infectivity assays. Cotransfection of human 293T cells with these proviral constructs and plasmids expressing CAEV, MVV, or vesicular stomatitis virus envelope glycoproteins produced infectious pseudotyped virus which induced resistance of infected cells to G418. Using these pseudotypes, we confirmed the wide species distribution of Icelandic MVV receptors and the narrow host range of CAEV. However, functional receptors for the two North American MVV strains tested, unlike the Icelandic MVV and similar to CAEV, were limited to cells of ruminant species, regardless of cytopathic phenotype. The results indicate a differential receptor recognition by MVV strains which is unrelated to cytopathic phenotype.
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PMID:Host range of small-ruminant lentivirus cytopathic variants determined with a selectable caprine arthritis- encephalitis virus pseudotype system. 1146 10