Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound   Target Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound

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Query: EC:2.7.7.49 (reverse transcriptase)
31,746 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Dendritic cells (DC) act as potent primary antigen-presenting cells in many immune responses and therefore may have a role in the initiation and perpetuation of the synovial inflammation in chronic inflammatory arthritis. To examine their function, it is important to isolate fresh DC from arthritic joints without aberrant activation. We have developed a technique using minimal cell manipulation to isolate DC from the synovial fluid of chronic arthritic patients. Using this method, DC were shown to be potent allostimulatory cells, with 63-90% of cells lacking lineage-specific markers (lin-), but positive for MHC class II molecules. Two morphologically distinct populations of these cells were identified in 10 out of 13 DC preparations. Both populations expressed CD40, intercellular adhesion molecule-1 (ICAM-1), ICAM-2, ICAM-3 and leucocyte function associated antigen-3 (LFA-3), but the predominant population, which was larger and more typical of cultured blood DC, had a higher density of these antigens compared with the minor population, which were smaller and morphologically similar to lymphocytes. Two new MoAbs which label activated human blood DC, HB15 (CD83) and CMRF-44, were tested. CD83 labelled very weakly or not at all, whereas CMRF-44 was positive on the larger cells only. Likewise, the costimulator molecule, B7/BB1 (CD80), was not detected on the surface of either synovial lin- cell population, reverse transcriptase polymerase chain reaction (RT-PCR) showed little or no CD80 mRNA, and no binding of the CTLA-4Ig fusion protein was found. These results suggest that synovial DC are not, despite the inflammatory environment, in a fully activated state.
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PMID:Dendritic cells in synovial fluid of chronic inflammatory arthritis lack CD80 surface expression. 753 11

CD44 is a cell-surface glycoprotein postulated to play a role in a variety of biological processes, including lymphocyte homing and tumor-cell metastasis. Several isoforms of CD44 have been identified in human cells, and the genesis of some of these isoforms has been attributed to alternative splicing. In the study presented here we amplified three novel transcript variants of CD44 from human cell lines using a reverse transcriptase-polymerase chain reaction strategy. Two of the novel isoforms differed from previously described CD44 isoforms as a result of alternative splicing that occurred at previously reported splice junctions. The third novel CD44 isoform was generated from a previously unreported alternative splice junction near the 5' end of the open reading frame. Southern blot analysis of genomic DNA revealed that these novel isoforms and all of the previously described CD44 isoforms arose from alternative splicing. The capability of cells to modify their CD44 alternative splicing pattern was demonstrated in MCF-7 cells, which altered their CD44-isoform expression pattern in response to treatment with hyaluronidase. A better understanding of mechanisms regulating CD44 alternative splicing may provide insights into diverse processes, including tumor-cell metastasis and lymphocyte homing.
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PMID:Novel variants of CD44 arising from alternative splicing: changes in the CD44 alternative splicing pattern of MCF-7 breast carcinoma cells treated with hyaluronidase. 835 81

CD44 is a ubiquitous cell-surface glycoprotein that displays many variant isoforms (CD44v) generated by alternative splicing of exons 2v to 10v. The expression of variant isoforms is highly restricted and correlated with specific processes, such as leukocyte activation and malignant transformation. We have herein studied CD44v expression in acute myeloid leukemia (AML) and, for comparison, in normal myelopoiesis. Protein expression of total CD44 and of CD44-3v, -6v, and -9v isoforms has been measured using specific monoclonal antibodies and flow cytometry. The composition of variant exon transcripts has been analyzed by semi-quantitative reverse transcriptase-polymerase chain reaction followed by Southern hybridization with exon-specific probes. Our data show that (1) CD44-6v isoforms are expressed on 12.0% +/- 2.5% of normal CD34(+) cells; this expression is sharply upregulated through monopoiesis and, inversely, downregulated during granulopoiesis. Also, CD44-3v and CD44-9v isoforms are detected on 10% and 14% of normal monocytes, respectively. (2) Sixty-nine from a total of 95 AML patients display a variable proportion (range, 5% to 80%) of CD44-6v+ leukemic cells. (3) A shorter overall survival characterizes the group of AML patients displaying more than 20% of CD44-6v+ leukemic cells (8 months v 18 months, P < .02). These data suggest, for the first time, that the protein expression of CD44-6v containing isoforms may serve as a new prognostic factor in AML.
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PMID:A strong expression of CD44-6v correlates with shorter survival of patients with acute myeloid leukemia. 955 99

Human CD83 (hCD83) is a 45 000 Mr cell-surface protein expressed predominantly by dendritic lineage cells. In this report, the genomic locus encoding mouse CD83 (Cd83) was isolated and the gene structure determined. The Cd83 gene spans approximately 19 kilobases (kb) and is composed of five exons, with two exons encoding a single extracellular immunoglobulin (Ig)-like domain. Mouse CD83 (mCD83) cDNAs were isolated by reverse transcriptase polymerase chain reaction of mouse RNA. Sequence determination revealed substantial conservation, with mCD83 and hCD83 sharing 63% amino acid identity. The transmembrane and cytoplasmic regions of CD83 were most highly conserved. Mouse CD83 mRNA of 2.4 kb was abundantly expressed in spleen and brain, but could also be detected in most tissues analyzed. These results suggest that in the mouse, as in humans, widely distributed dendritic cells may express mCD83. Chromosome localization revealed that the Cd83 gene is present on mouse chromosome 13 band A5, while the locus for the human gene (CD83) is located within a homologous region of human chromosome 6p23. Thus, the CD83 protein and gene appear to be well conserved during recent mammalian evolution. The isolation and characterization of the mCD83 cDNA and gene provides important information and tools that will facilitate the study of CD83 and dendritic cell function in a mouse model system.
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PMID:The mouse Cd83 gene: structure, domain organization, and chromosome localization. 979 34

CD43/leukosialin is a major sialoglycoprotein of the dendritic cell (DC) surface, which can regulate cell adhesion and has the potential to mediate cell activation signals. Monocyte-derived DC transiently incubated with the anti-CD43 mAb, MEM-59, or with F(ab')2 fragments, but not with monovalent Fab fragments or control IgG, 24 h later showed increased levels of membrane HLA-DR, CD54, CD40, CD80, CD86, and CD83. In parallel, CD43 cross-linking induced synthesis and release of IL-1beta, IL-6, TNF-alpha, IL-12, and IL-10. CD43 ligation inhibited the endocytic activity of DC, and enhanced the capacity of DC to stimulate T cell proliferation in the primary allogeneic and autologous MLR assay. In addition, anti-CD43-treated DC were less efficient at presenting native HIV-1 reverse transcriptase to a specific CD4+ T cell clone, whereas presentation of the reverse transcriptase 55-72 peptide to the same clone was increased. Finally, MEM-59 or its F(ab')2 fragments elicited a rise in intracellular free calcium and tyrosine phosphorylation of a 25-kDa protein in DC. The results thus indicate that CD43 cross-linking with specific ligands induces activation and functional maturation of DC.
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PMID:Cross-linking of membrane CD43 mediates dendritic cell maturation. 1035 44

Dendritic cells (DC) have been implicated in the initial selection for macrophage-tropic HIV-1 during transmission and in the generation of high-level virus replication during interactions with CD4 T cells. The role of DC as viral reservoirs and the extent of productive infection is unclear, but the ability to generate large numbers of DC from blood monocytes has produced a tractable model for study of DC-HIV-1 interactions. When cultured in granulocyte-macrophage colony stimulating factor and IL-4, sorted CD14+ monocytes rapidly lost phagocytic function for both 93 nm and 977 nm latex particles and developed the surface markers and function of DC. After 7 days, when returned to medium containing human serum without cytokines, some monocyte-derived dendritic cells (MDDC) became adherent, but retained the costimulatory markers CD80 and CD86 and continued to express CD83 and CD40. The MDDC stimulated allogeneic CD4 T cells, did not express new macrophage markers and remained non-phagocytic. With or without TNF-alpha, MDDC generated in cytokines were infected by macrophage and T cell-tropic virus and produced higher reverse transcriptase levels than did the autologous monocyte-derived macrophages (MDM). When added to T cells, the infected MDDC were able to infect T cells with a wider range of viral isolates than were MDM.
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PMID:Monocyte-derived dendritic cells as a model for the study of HIV-1 infection: productive infection and phenotypic changes during culture in human serum. 1054 Feb 11

The functions of Thy-1, a 35-kDa cell-surface glycoprotein, and its natural ligand are still unknown. Anchoring to the membrane via linkage to phosphatidyl-inositol (PI) raises the possibility of cleavage off the membrane by PI-specific phospholipases. Soluble Thy-1 (sThy-1) could interfere with the binding of the unknown natural ligand followed by regulation of different cell functions. In this study we established an enzyme-linked immunosorbent assay (ELISA) to measure and quantify sThy-1 in serum and wound fluid. Recombinant human Thy-1 (rhThy-1) was expressed in Drosophila S2 cells, purified from culture supernatant and used as standard for quantitation of sThy- by the ELISA technique. There were no differences in sThy-1 levels in serum of healthy donors and patients with systemic sclerosis, leg ulcers, or rheumatoid arthritis, respectively, detected by ELISA. In contrast, at the local site of inflammation, in wound fluid of venous leg ulcers and in synovial fluid from joint puncture, we found strongly elevated levels of sThy-1 compared with sThy-1 in the serum of the same patient. Thy-1 is expressed in humans on brain cells, fibroblasts, a subpopulation of CD34+ blood stem cells, and possibly activated human dermal microvascular endothelial cells. In this study, we never found Thy-1 mRNA or protein expression in resting endothelial cells as shown by reverse transcriptase polymerase chain reaction (RT-PCR) and flow-cytometry. Thy- expression could be induced on endothelial cells by phorbol myristate acetate and to a lesser extent by tumor necrosis factor-alpha (TNF-alpha). In situ, monoclonal antibodies to Thy-1 did not stain endothelial cells in normal skin, whereas endothelial cells in the synovial membrane of rheumatoid arthritis patients and endothelial cells surrounding melanoma express Thy-1. In summary, our data indicate that Thy-1 is present in soluble form in serum. Furthermore, Thy-1 seems to be a marker for endothelial cell activation. Therefore, activated endothelial cells as well as fibroblasts might be a possible source of sThy-1.
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PMID:Detection of human soluble Thy-1 in serum by ELISA. Fibroblasts and activated endothelial cells are a possible source of soluble Thy-1 in serum. 1057 Nov 19

It has been reported previously that in vitro treatment of human blood derived dendritic cells (DC) with contact allergens provokes the elevated expression of mRNA for interleukin (IL) 1beta, under conditions where similar treatment of cells with the non-sensitizing skin irritant sodium lauryl sulfate (SLS) did not alter IL-1beta mRNA levels (Reutter et al., 1997). The purpose of the present investigation was to evaluate further this phenomenon and to explore the potential utility of this approach for the purpose of skin sensitization testing. Human peripheral blood progenitor cells prepared from healthy adult volunteers were cultured in the presence of IL-4 and granulocyte/macrophage colony stimulating factor. After 5 days of culture, the majority of cells had a Langerhans cell-like phenotype, with characteristic dendritic morphology and cell surface expression of CD83, major histocompatibility complex class II and CD1a determinants. These blood-derived DC were cultured in the presence of the contact allergen 2,4-dinitrofluorobenzene (DNFB), SLS or vehicle alone and mRNA expression for IL-1beta, IL-6 and IL-18 was analysed by semiquantitative reverse transcriptase polymerase chain reaction. Constitutive expression of all three cytokines was observed for DC isolated from all donors examined. Exposure to DNFB resulted in upregulation of IL-1beta mRNA (two- to threefold) in cells derived from three out of eight donors whereas IL-6 and IL-18 were largely unaffected by allergen exposure. In contrast, SLS treatment did not induce IL-1beta mRNA expression in any of the donors investigated. Analysis of cytokine mRNA expression using the protocol described by Reutter et al. (1997), did not increase the sensitivity of measurement of induced cytokine expression. Although selected upregulation of IL-1beta by blood derived DC has been confirmed, a wider range of contact allergens and irritants need to be assessed before this approach could be considered for hazard identification.
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PMID:Investigation of induced changes in interleukin 1beta mRNA expression by cultured human dendritic cells as an in vitro approach to skin sensitization testing. 1090 42

Bone marrow abnormalities are frequently observed in HIV-1-infected individuals. Infection of marrow mesenchymal stem cells (MSCs) may abrogate their growth properties and hematopoietic supportive functions. To delineate the cell type infected, and factors responsible for the deleterious effects, human bone marrow cells were exposed to HIV-1 in vitro. By week 4, the ability of MSCs to form colonies of purely fibroblasts (CFU-F) and mixed colonies of fibroblasts and adipocytes (CFU-FA) was suppressed by 23 +/- 5 and 55 +/- 7%, respectively. The p24 concentration in culture supernatants steadily declined from 170 ng/ml in the inoculum to 134 +/- 30, 35 +/- 15, 2.3 +/- 3, and <0.02 ng/ml at the end of week 1, 2, 3, and 4, respectively. However, even at week 4, coculturing with MT-4 lymphocytes for 1 week dramatically increased p24 levels. Polymerase chain reaction (PCR) amplification, using HIV-1-specific primers, and in situ hybridization with an HIV-1 cDNA probe demonstrated the presence of virus-specific nucleic acids within stromal colonies. Coimmunostaining with antibody to CD83 implicated the presence of HIV-1 within dendritic progenitor cells. Immunostaining with HIV-1 Tat antibody demonstrated the presence of Tat protein and reverse transcriptase (RT)-PCR assays showed increased (160-220%) mRNA levels for inflammatory cytokines (tumor necrosis factor alpha [TNF-alpha], interleukin 1beta [IL-1beta], IL-6, and macrophage inflammatory protein 1alpha [MIP-1alpha]). A concentration-dependent decrease in CFU-STROs was observed on incubation with either Tat protein (1-100 ng/ml) or with TNF-alpha or IL-1beta (0.025-25 ng/ml). These results suggest that HIV-1 infection of stromal cells may produce inhibitory factors that suppress the clonogenic potential of MSCs.
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PMID:Suppression of clonogenic potential of human bone marrow mesenchymal stem cells by HIV type 1: putative role of HIV type 1 tat protein and inflammatory cytokines. 1223 Sep 35

Platelets are generally believed to be inactive in terms of de novo protein synthesis. On the other hand, the presence of ribosomes and mRNA molecules is well established. Many studies have used reverse transcriptase (RT) -PCR for detection of gene transcripts in platelets. As RT-PCR is a very sensitive method, any leukocyte contamination of platelet preparations can lead to false results. We performed three filtration procedures to minimize leukocyte contamination of pooled buffy-coat platelet concentrates prior to RNA isolation. Furthermore, by applying a genomic PCR approach with 50 amplification cycles we demonstrated that nucleated cells were not detectable. Microarray hybridization was used to analyze 9,850 individual human genes in RNA from purified platelets. In total we identified 1,526 (15.5%) positive genes. The data were confirmed in six individual experiments each performed on a PC pooled from four individual blood donations. Genes specific for nucleated blood cells such as CD4, CD83 and others were negative and verified the purity of PC. Overrepresentation of positive genes was found in the functional categories of glycoproteins/integrins (22.6% vs. 15.5%, p=0.029) and receptors (20.7% vs. 15.5%, p<0.001). Gene transcripts encoding RANTES, GRO-alpha, MIP-1alpha, MIP-1beta, and others were found at high levels of signal intensity and confirmed literature data. This work provides a mRNA profile of human platelets and a complete list of results can be downloaded from the website of our institute www.ma.uni-heidelberg.de/inst/iti/plt_array.xls. The knowledge about gene transcripts may have an impact on the characterization of novel proteins and their functions in platelets.
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PMID:Messenger RNA profiling of human platelets by microarray hybridization. 1451 72


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