Biomedical subjects

D Bevec

Publications and source records attributed to D Bevec.

At least 37 records · Page 2Linked to original sources

PubMed1994

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.

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.

Cell Line↗

PubMed1994

Constitutive expression of chimeric neo-Rev response element transcripts suppresses HIV-1 replication in human CD4+ T lymphocytes.

We have previously reported that chimeric neomycin phosphotransferase (neo)-Rev response element (RRE) transcripts suppress the function of the human immunodeficiency virus type 1 (HIV-1) Rev trans-activator protein in HeLa cells. In an extension of these experiments, human CD4+ CEM cells (G418-resistant cell populations and clonal isolates) stably expressing chimeric neo-RRE genes (2, 3, or 6 RRE copies) were generated using retroviral-mediated gene transfer. The transduced CEM clones were infected with the HIV-1 HTLVIIIB isolate and the following three phenotypes were observed: (i) the transduced CEM cells were readily infected with HIV-1 indistinguishable from the control CEM cells; (ii) the appearance of HIV-1 replication markers was significantly delayed; (iii) no signs of HIV-1 replication were detectable although proviral HIV-1 DNA sequences could be detected in these cells. Furthermore, HIV antigen expression was limited in neo-resistant CEM cell populations inoculated with the HIV-1 HTLVIIIB isolate. Only 10% of the CEM-pX17-3xRRE cells and 20% of the CEM-pX17-2xRRE cells displayed HIV-1 antigens 43 days after challenge and had retained CD4 surface expression on 47% and 64% of the cells, respectively. In sharp contrast, 80% of the CEM-pX17 or the CEM-pX17-6xRRE cells expressed HIV-1 antigens but no CD4 antigens were detectable in these cultures. These results clearly indicate that RRE decoys could be developed into an effective somatic gene therapy approach against HIV-1 induced acquired immunodeficiency syndrome (AIDS).

Base Sequence↗

PubMed1994

Modulation of pyrogen-induced upregulation of endothelial cell adhesion molecules (CAMs) by interleukin-4: transcriptional mechanisms and CAM-shedding.

The pyrogens interleukin 1 (IL-1), tumor necrosis factor (TNF), and bacterial lipopolysaccharides (LPS) are known to increase endothelial cell (EC) adhesiveness for leukocytes by stimulating surface expression of various adhesion molecules. IL-4, a product of activated T-cells, was shown to affect pyrogen-mediated regulation of EC adhesion molecule surface expression. In the present study, we investigated the effect of IL-4 on pyrogen-induced upregulation of the cell adhesion molecules (CAMs) ICAM-1 (intercellular cell adhesion molecule-1), ELAM-1 (endothelial leucocyte adhesion molecule-1), and VCAM-1 (vascular cell adhesion molecule-1) in cultured human umbilical vein EC (HUVEC). Surface expression of adhesion molecules was quantified by flow cytometry, HUVEC mRNA content was estimated by Northern blot analysis, and ICAM-1 antigen in conditioned media was measured by ELISA. Incubation of HUVEC with IL-1 (100 U/ml), TNF (500 U/ml), and LPS (10 micrograms/ml) caused significant increase in ICAM-1, ELAM-1, and VCAM-1 surface expression; IL-1 caused about an eightfold increase in ICAM-1 expression, about a 13-fold increase in ELAM-1 surface expression, and about a fourfold increase in VCAM-1 expression. Coincubation of pyrogens with IL-4 (500 U/ml) differentially influenced their proadhesive effects on the HUVEC surface. In the presence of IL-4, IL-1-induced ICAM-1 upregulation was reduced, ELAM-1 upregulation was not significantly influenced by IL-4, and induction of VCAM-1 was enhanced by IL-4.(ABSTRACT TRUNCATED AT 250 WORDS)

Base Sequence↗

PubMed1993

Eukaryotic initiation factor 5A is a cellular target of the human immunodeficiency virus type 1 Rev activation domain mediating trans-activation.

Expression of human immunodeficiency virus type 1 (HIV-1) structural proteins requires the presence of the viral trans-activator protein Rev. Rev is localized in the nucleus and binds specifically to the Rev response element (RRE) sequence in viral RNA. Furthermore, the interaction of the Rev activation domain with a cellular cofactor is essential for Rev function in vivo. Using cross-linking experiments and Biospecific Interaction Analysis (BIA) we identify eukaryotic initiation factor 5A (eIF-5A) as a cellular factor binding specifically to the HIV-1 Rev activation domain. Indirect immunofluorescence studies demonstrate that a significant fraction of eIF-5A localizes to the nucleus. We also provide evidence that Rev transactivation is functionally mediated by eIF-5A in Xenopus oocytes. Furthermore, we are able to block Rev function in mammalian cells by antisense inhibition of eIF-5A gene expression. Thus, regulation of HIV-1 gene expression by Rev involves the targeting of RRE-containing RNA to components of the cellular translation initiation complex.

Amino Acid Sequence↗

PubMed1993

Tumor necrosis factor alpha and interleukin-1 beta mRNA expression in HMC-1 cells: differential regulation of gene product expression by recombinant interleukin-4.

Cytokine-activation pathways in mast cells are supposed to play a significant role in host defense mechanisms and allergic reactions. Interleukin-4 (IL-4) is a well-characterized regulator of growth and function of mast cells. The human mast cell line HMC-1 was established from a patient suffering from mast cell leukemia and was shown to expose IL-4 binding sites. In the present study, the effects of recombinant human (rh) IL-4 and other rh cytokines (IL-2, IL-3, IL-6, IL-8) on expression of cytokine mRNA in HMC-1 cells were examined by Northern blot analysis using oligonucleotide probes. Tumor necrosis factor alpha (TNF-alpha) and IL-1 beta transcripts were found to be expressed constitutively in HMC-1 cells, whereas transcripts for IL-3, IL-4, IL-5, IL-6, and granulocyte-macrophage colony-stimulating factor (GM-CSF) could not be detected. Of all cytokines tested, rhIL-4 was found to down-regulate IL-1 beta mRNA expression and formation of immunoreactive IL-1 beta protein in HMC-1 cells. The effect of IL-4 on IL-1 beta gene product expression was time- and dose-dependent (maximum effects obtained with 100 U/mL of rhIL-4). No effect of IL-4 on expression of TNF-alpha mRNA in HMC-1 cells was observed. These results raise the possibility that human mast cells are a source of both TNF-alpha and IL-1 beta. Furthermore, our study provides evidence that IL-4 regulates IL-1 beta gene product expression in HMC-1 cells. The HMC-1 cell line should be a useful tool for studying cytokine activation pathways in human mast cells.

Base Sequence↗

PubMed1992

Inhibition of human immunodeficiency virus type 1 replication in human T cells by retroviral-mediated gene transfer of a dominant-negative Rev trans-activator.

Human immunodeficiency virus type 1 (HIV-1) is the causative agent of the acquired immunodeficiency syndrome (AIDS). Currently, no satisfactory treatment for this viral disease is available. Somatic gene therapy has been proposed as an alternative to conventional therapies. Several antiviral gene therapy approaches including ribozymes, antisense inhibition, and RNA-decoy strategies, as well as dominant-negative mutants of HIV-1 proteins (Gag, Tat, and Rev) have been suggested. To prove the concept of trans-dominant inhibition of HIV-1 replication, we transduced CEM cells with a retroviral vector encoding a dominant-negative rev gene. Amplification of integrase-specific proviral sequences from high molecular weight DNA indicated successful HIV-1 human T-lymphotropic virus type IIIB (HTLV-IIIB) infection of all cells. In contrast to CEM cells and CEM cells expressing the rev wild-type (wt) gene, infection of two CEM-RevM10 clones with HIV-1 did not result in the release of significant levels of p24 Gag antigen as measured by antigen capture assay, indicating a block in HIV-1 replication due to the presence of the trans-dominant Rev protein. Furthermore, the parental CEM cells as well as CEM cells expressing the Rev wt protein were effectively killed in the course of the HIV-1 infection, whereas all CEM cells expressing the RevM10 protein were unaffected in their growth rate.

Base Sequence↗

PubMed1992

Specific inhibition of mRNA accumulation for lymphokines in human T cell line Jurkat by mycobacterial lipoarabinomannan antigen.

The immunomodulatory effect of Mycobacterium tuberculosis-derived lipoarabinomannan (LAM) on mitogen/antigen-induced expression of mRNAs for a number of cytokines in human monocytic cell line Mono-Mac-6 and in T cell line Jurkat was investigated. Interestingly, LAM exhibited a down-regulatory effect on the accumulation of mRNAs for IL-2, IL-3, granulocyte-macrophage colony-stimulating factor (GM-CSF), and IL-2 receptor alpha (IL-2R alpha) in T cells co-stimulated with phytohaemagglutinin-P (PHA) and 4 beta-phorbol-12-myristyl-13-acetate (PMA). In human Mono-Mac-6 cells. LAM has a weak inhibitory effect on the lipopolysaccharide (LPS)-induced mRNA accumulation for IL-1 beta, a slight stimulatory effect on mRNAs accumulation for IL-8 and tumour necrosis factor-alpha (TNF-alpha), but clearly no effect on mRNA accumulation for intercellular adhesion molecule-1 (ICAM-1). These findings imply that LAM may contribute to the immunologic defects associated with a number of mycobacterial infections by modulating these mediators.

Antigens, Bacterial↗

PubMed1992

Selection of a muramyl peptide based on its lack of activation of nuclear factor-kappa B as a potential adjuvant for AIDS vaccines.

Activation of the cellular transcription factor nuclear factor-kappa B (NF-kappa B) by cytokines and other immunostimulants has been tightly linked with enhanced replication of human immunodeficiency virus-type 1 (HIV-1) in infected cells. Various immunomodulators are currently being examined in animal and human trials for their suitability as adjuvants in potential vaccines against acquired immunodeficiency syndrome (AIDS). It may prove to be beneficial to select adjuvants that do not induce NF-kappa B activation and particularly if the vaccines are to be aimed at seropositive individuals. We have examined a battery of synthetic immunostimulants of the muramyl peptide family for their ability to activate NF-kappa B in human and mouse cell lines. In this report, we demonstrate selective activation of NF-kappa B in different cell lines and by different muramyl peptides possessing immunostimulatory activities. The mechanism of such activation is apparently via production of reactive oxygen intermediates (ROI) since pretreatment of cells with antioxidants blocked subsequent activation of NF-kappa B. However, among all the molecules tested only one lipophilic, non-pyrogenic adjuvant active muramyl peptide showed a complete lack of NF-kappa B activation in all cell lines tested. This molecule could well become the adjuvant of choice in future AIDS vaccines.

Acetylmuramyl-Alanyl-Isoglutamine↗

PubMed1991

IL-4 regulates c-kit proto-oncogene product expression in human mast and myeloid progenitor cells.

The c-kit proto-oncogene encodes the receptor for a novel hemopoietic cytokine, termed stem cell factor (SCF) or mast cell growth factor (MGF) according to its stimulating spectrum. The human receptor for SCF/MGF is expressed in a subset of normal bone marrow progenitor cells, in leukemic myeloid cells, and in mast cells. In the present study, the effects of recombinant human growth regulators (IL-1 through -9, granulocyte-macrophage/granulocyte/macrophage-CSF, IFN, and TNF) on c-kit proto-oncogene product expression were analyzed by indirect immunofluorescence, by using the anti-SCF/MGFR mAb YB5.B8, and Northern blot analyses, by using a c-kit oligonucleotide probe. Of all cytokines tested, IL-4 was found to down-regulate expression of YB5.B8 Ag in the human mast cell line HMC-1 (maximum inhibition, 51.05 +/- 16.36% mean fluorescence intensity of control; p less than 0.02), as well as in primary leukemic myeloid cells. IL-4 was also found to down-regulate expression of YB5.B8 Ag in normal enriched bone marrow progenitor cells. The effects of IL-4 on expression of YB8.B8 Ag in myeloid/mast cell progenitors was dose and time dependent (maximum effects observed on days 2 and/or 4, by using 50 U/ml of rIL-4) and could be neutralized by using anti-IL-4 mAb. Moreover, IL-4 was found to down-regulate expression of c-kit mRNA in leukemic myeloid cells as well as in HMC-1 cells. Together, these observations identify IL-4 as a regulator of c-kit proto-oncogene product expression in the human system. The effects of IL-4 on human hemopoietic progenitor cells and mast cells may be mediated in part through regulation of SCF/MGFR expression.

Antibodies, Monoclonal↗

PubMed1991

Interleukin-4 counteracts pyrogen-induced downregulation of thrombomodulin in cultured human vascular endothelial cells.

Inflammatory mediators such as tumor necrosis factor (TNF) or interleukin-1 (IL-1) and bacterial lipopolysaccharides (LPS) were shown to shift the hemostatic balance of the endothelial cell (EC) surface in favor of procoagulant activities by inducing tissue factor (TF) expression and downregulation of thrombomodulin (TM). In the present study, the effects of IL-4 on these regulatory mechanisms were investigated using cultured human umbilical vein EC. TM downregulation induced by the pyrogens IL-1 (100 U/mL), TNF (500 U/mL), and LPS (20 micrograms/mL) to less than 50% of TM activity of untreated cells during a 12-hour incubation period was completely neutralized when these mediators were coincubated with IL-4 (100 U/mL). In accordance with TM surface activity, TM messenger RNA was decreased by IL-1, TNF, and LPS to less than 40% of untreated cells; this effect was in part antagonized by IL-4. No influence of IL-4 on EC tissue factor induction by IL-1, TNF, and LPS was found. Binding studies using 125I-radiolabeled IL-4 suggest that EC express a single class of high-affinity binding sites (kd = 3.2 pmol/L; 2,000 to 2,500 receptors per cell). These results show that IL-4, in part, protects the EC surface against pyrogen-induced procoagulant changes. Transcriptional regulatory mechanisms seem to be involved in EC surface TM regulation.

Cell Membrane↗

PubMed1991

Interleukin 4 promotes expression of mast cell ICAM-1 antigen.

Cell recognition molecules play a crucial role in the regulation of immune cells. We recently found that mast cells (MCs) express leukocyte recognition molecules, including ICAM-1 antigen, a natural ligand of LFA-1. We here report that interleukin 4 (IL-4), a pleiotropic cytokine and mast cell differentiation factor, selectively promotes expression of surface ICAM-1 antigen and ICAM-1 mRNA in human MCs. IL-4 also up-regulates ICAM-1 antigen in cells of monocyte/macrophage lineage but has no effect on ICAM-1 antigen expressed on basophils, fibroblasts, or lymphocytes. The increase in expression of mast cell/macrophage ICAM-1 antigen induced by IL-4 may contribute to the accumulation of leukocytes and facilitate cell-contact-dependent regulation of immune cells in inflamed tissues.

Antigens, CD↗

PubMed1991

Developmental and tissue-specific expression of the Q5k gene.

Expression of the Q5k gene was examined by northern blot analysis and polymerase chain reaction (PCR) in the AKR mouse and various cell lines, each of the H-2k haplotype. Our results show that Q5k mRNA is present during the whole postimplantational development of the AKR embryo/fetus (gestation day 6 to 15). In the juvenile mouse (week 2 to 4) transcription of the Q5k gene persisted in all organs examined. In contrast, in the adult animal expression of the Q5k gene was limited to the thymus and uterus of the pregnant mouse. Upon malignant transformation, the amount of Q5k-specific mRNA increased dramatically in thymus and could also be observed in the spleen of thymoma bearing animals. Expression of the Q5k gene was also detectable in several transformed mouse cell lines. Mitogen stimulation or treatment with cytokines induced Q5k expression in primary spleen cell cultures. A possible explanation for the tissue-restricted expression in the adult AKR mouse is discussed.

Aging↗

PubMed1991

trans-activation of the HIV-1 LTR by the HIV-1 Tat and HTLV-I Tax proteins is mediated by different cis-acting sequences.

Human immunodeficiency virus type 1 (HIV-1) gene expression is regulated by viral and cellular factors interacting with cis-elements located in the retroviral long terminal repeat (LTR). In this report we analyzed HIV-1 LTR-specific regulatory sequences responsive to the HIV-1 Tat and HTLV-I Tax trans-activator proteins. Our results indicate that the Sp1 binding sites in the HIV-1 LTR are crucially involved in Tat-mediated gene expression in human Jurkat T-cells whereas they are dispensable for HTLV-I Tax-induced activation. In contrast, the NF-kB binding sites within the HIV-1 LTR are essential for Tax-mediated transcription but had only marginal effect on Tat-induced reporter gene expression.

Animals↗

PubMed1989

Biosynthesis of complement C4 messenger RNA in normal human kidney.

Complementary DNA (cDNA) probes were used to investigate the extrahepatic production of the major histocompatibility complex (MHC)-linked complement components C4, factor B and C2 in various normal human tissues. The presence of the corresponding messenger RNA (mRNA) was tested by Northern blot analysis. Complement C4 mRNA was found in liver, and with high intensity also in normal kidneys. In contrast, no C2 mRNA and only very low amounts of factor B mRNA could be detected in the kidney. Slot blot hybridization was performed to quantitate the amount of C4 mRNA, and the intensity of C4 mRNA hybridization in the kidney samples was about 25% compared with liver RNA. C4-specific transcripts were not present in isolated glomeruli but in the renal interstitium. Other human tissues, such as tonsil, spleen, thymus, brain, lung and peripheral mononuclear cells, contained no C4 mRNA. Low amounts of C4 mRNA were found in colon, thyroid gland, lymph node and breast carcinoma. The results obtained with lung, where C2 mRNA was found but no C4 mRNA, further indicate an independent, tissue-specific regulation of the class III gene expression. The results, showing that the complement C4 genes are transcribed very efficiently in normal human kidney, suggest a direct role of complement C4 in renal pathogenesis.

Adult↗

PubMed1988

Sequence of the mouse Q4 class I gene and characterization of the gene product.

The Q4 class I gene has been shown to participate in gene conversion events within the mouse major histocompatibility complex. Its complete genomic nucleotide sequence has been determined. The 5' half of Q4 resembles H-2 genes more strongly than other Q genes. Its 3' end, in contrast, is Q-like and contains a translational stop signal in exon 5 which predicts a polypeptide with an incomplete membrane spanning segment. The presence of two inverted B1 repeats suggests that part of the Q4 gene may be mobile within the genome. Gene transfer experiments have shown that the Q4 gene encodes a beta 2-microglobulin associated polypeptide of Mr 41,000. A similar protein was found in activated mouse spleen cells. The Q4 polypeptide was found to be secreted both by spleen cells and by transfected fibroblasts and was not detectable on the cell surface. Antibody binding and two-dimensional gel electrophoresis indicate that the Q4 molecule is identical to a mouse class I polypeptide, Qb-1, which has been previously described.

Amino Acid Sequence↗

PubMed1985

Control of synthesis and expression of H-2 heavy chain and beta-2 microglobulin in AKR leukemias.

In a series of newly isolated AKR leukemias, some tumors expressed large amounts of both H-2K and H-2D molecules, while others had reduced levels of both antigens. The number of H-2 antigens expressed in steady state showed a consistent correlation with the rate of synthesis of the H-2 class I heavy chain and the beta-2 microglobulin (beta 2m) light chain, and with the amount of H-2- and beta 2m-specific mRNA present in the tumors. Stimulation of leukemic cells with interferon induced an increased transcription of both H-2 and beta 2m mRNA. These results suggest that there is a mechanism that regulates, at the transcriptional level, the coordinate expression of H-2K and H-2D heavy chains, and the beta 2m light chains encoded by genes on chromosomes 17 and 2, respectively.

Animals↗

PubMedDate not supplied

Aberrant MHC antigens in a sarcoma virus-induced mouse tumour.

From a series of mouse sarcomata, newly induced by Rous sarcoma virus (RSV), the DOH cell line was shown to lack expression of syngeneic H-2Kd and Dk antigens (Noll et al., 1986). It unexpectedly displayed determinants specific for H-2Kk molecules. Interferon treatment of DOH stimulated the expression of H-2Kk determinants and also the display of some, but not all, determinants of the syngeneic H-2Kd molecules. H-2Dk expression was not stimulated. Southern blot hybridization of genomic DNA digests from DOH cells confirmed the identity of the H-2K region with that from syngeneic C3H.OH liver cells, but also showed changes in the pattern of restriction fragments that contain class I genes from the D and Qa regions. These results suggest that aberrant MHC class I molecules that carry H-2Kd- and H-2Kk-like determinants are expressed by DOH sarcoma cells. These molecules may act as target antigens for tumour-specific cytotoxic T cells elicited by injection of DOH cells into syngeneic mice.

Animals↗

PubMedDate not supplied

Organization of the AKR Qa region: structure of a divergent class I sequence, Q5k.

We established the organization of the AKR Qa region and determined the sequence of the Q4 and Q5 genes. Restriction mapping and genomic Southern blot analysis revealed that the AKR strain codes for only three H-2K homologous genes in this region. The AKR Q5 gene is not homologous to the Q5 gene of the C57BL strain, but is presumably allelic to the Q5 gene isolated from Balb/c. The organization and structure of the AKR Qa family is virtually identical to the Qa genes of the C3H mouse. The AKR Q5 gene, in contrast to other H-2K homologous Qa region genes, codes for a typical transmembrane region, and upon transfection into BHK cells, a 1.6 kb Q5 transcript is detected.

Amino Acid Sequence↗