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:2.7.7.48 (transcriptase)
9,479 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Feline leukemia virus, subgroup C/Sarma (FeLV-C/Sarma) induces pure red blood cell aplasia in cats. Although erythroid (BFU-E and CFU-E) and granulocyte/macrophage (CFU-GM) progenitors are infected with this virus, only erythropoiesis is impaired. Two to 3 weeks before the onset of anemia, CFU-E become undetectable in marrow cultures while earlier erythroid progenitors (BFU-E) persist, suggesting that FeLV-C/Sarma (presumably via its envelope glycoprotein gp70) inhibits the differentiation of BFU-E to CFU-E in vivo. To correlate in vitro observations with the progression of disease, prospective studies were performed in six cats. These studies showed that at the time that the frequencies of CFU-E decreased in marrow cultures, BFU-E no longer responded to hematopoietic growth factor(s), although the responses of CFU-GM were unchanged. In further studies, anemic cats received suramin, a reverse-transcriptase inhibitor with other diverse effects. Within 4 to 14 days, erythropoiesis improved and up to 1,616 CFU-E were detected per 10(5) marrow mononuclear cells. However, progenitor cells remained infected, suggesting that suramin modulated erythroid differentiation without inhibiting progenitor infection. These observations led to the hypothesis that the gp70 of FeLV-C/Sarma impairs BFU-E differentiation by interference with ligand/receptor interactions or signal transduction pathways unique to erythroid cells. Understanding this mechanism should provide insights into the interactions controlling early erythropoiesis.
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PMID:Retrovirus-induced feline pure red blood cell aplasia: pathogenesis and response to suramin. 184 31

Transplantable erythroblastic leukemia was induced by 300-rad irradiation of C3H mice. Conditions for in vitro growth of the leukemic cells were studied. None of interleukin-3, granulocyte/macrophage colony-stimulating factor and erythropoietin could support the growth of the cells in vitro. In contrast, the leukemic cells grew into a stroma-dependent cell line, ELM-D, in close contact with the stromal cell layer of 900-rad-irradiated long-term bone marrow culture. A stroma-independent cell line, termed ELM-I-1, was further established from the non-adherent population in the co-culture of the leukemic cells, ELM-D, with stromal cells. Reverse transcriptase activity was not detectable in ELM-D or ELM-I-1 cells. Studies on binding and cross-linking of 125I-erythropoietin showed that ELM-I-1 cells had erythropoietin receptors, and two major radiolabeled protein products with molecular weights of 120 kDa and 140 kDa were detected on sodium dodecyl sulfate/polyacrylamide gel electrophoresis under reducing conditions.
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PMID:Stromal cell-dependent growth of leukemic cells from murine erythroblastic leukemia. 246 Apr 23

Peptides of melanosomal proteins have recently been shown to be recognized in an HLA-restricted mode by specific cytolytic T lymphocytes in melanoma patients. Dendritic antigen-presenting cells (DC) are considered to be the most effective stimulators of T cell responses, and the use of these cells has therefore been proposed to generate therapeutic responses to tumor antigens in cancer patients. We, therefore, generated DC from peripheral blood of normal donors in the presence of granulocyte/macrophage colony-stimulating factor and interleukin-4. Flow cytometric analysis of the cells during a 2-week culture revealed a loss of CD14 and CD34 expression, a concomittent increase of CD1a, CD11a,b and c, CD44, CD45, CD54, HLA-class I and II, and intermediate levels of CD26, CD80 and CD86. Cultured DC stimulated proliferation of allogeneic T cells and induced a marked, up to 20-fold, stimulation of T cell proliferation after pulsing with tetanus toxoid. To achieve independence of already-identified antigenic peptides presented in HLA class I-restricted fashion, which limits the general applicability of such peptides for vaccination of melanoma patients, we tested whether DC are transfectable with eukaryotic expression plasmids. DC transfected with two reporter genes (CAT, beta-galactosidase) using a liposome-based transfection technique, exhibited only low levels of enzymatically active proteins, but were able to degrade rapidly intracellular proteins and to process peptides efficiently. Chloramphenicol acetyltransferase as well as tyrosinase mRNA were detectable after transfection by reverse-transcriptase-polymerase chain reaction, and enzyme activities became measurable. Furthermore, DC transfected with the tyrosinase gene were able to induce specific T cell activation in vitro, indicating appropriate peptide processing and presentation in DC after transfection. These data suggest new approaches to future tumor vaccination strategies.
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PMID:Dendritic cells generated from peripheral blood transfected with human tyrosinase induce specific T cell activation. 748 49

Microvascular murine endothelial cells lines transformed by middle T oncogene of polyoma virus maintain the biological characteristics of nontransformed microvascular endothelial cells (EC). By using cell lines originated from different anatomical districts (thymus, brain, heart, and skin), we demonstrated that murine granulocyte-colony-stimulating factor (G-CSF) induces proliferation of murine microvascular endothelial cells at nanomolar concentrations without any cooperation with fetal calf serum. The proliferative effect on murine cells is less than that elicited by epidermal growth factor (EGF), used as standard for this function. G-CSF also promotes the migration of tEnd.1 endothelial cell line assayed by Boyden chamber technique. The analysis of transcript for G-CSF receptor (G-CSFR) by Northern blot hybridization and by reverse-transcriptase polymerase chain reaction (RT-PCR) shows that these cell lines have specific mRNA, with the size of that present in myeloid cells. These results indicate that G-CSF operates in the microvascular endothelial cells by a mechanism related to the presence of a specific receptor.
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PMID:Proliferative and migratory responses of murine microvascular endothelial cells to granulocyte-colony-stimulating factor. 768 23

Human peripheral blood granulocytes were analyzed for expression of interleukin-6 (IL-6) using reverse-transcriptase polymerase chain reaction (RT-PCR) and in situ hybridization. Neutrophil granulocytes from healthy donors were shown to express variable levels of IL-6. This expression was rapidly down-regulated after the removal of the cells from the circulating blood. In vitro culture of neutrophils abolished IL-6 expression, which could be reactivated by addition of GM-CSF to the culture medium. Constitutive expression of IL-6 was instead demonstrated in eosinophil granulocytes purified from normal donors and from a hypereosinophilic patient. In situ hybridization of unstimulated granulocytes confirmed that IL-6 expression occurs both in eosinophils and in neutrophils from peripheral blood. These findings show that granulocytes can actively contribute to cytokine expression in the peripheral blood and suggest their role in the afferent limb of the immune response, since by IL-6 production they might modulate T- and B-lymphocyte functions, granulocyte self-priming, and endothelial interaction.
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PMID:Interleukin-6 expression in human neutrophil and eosinophil peripheral blood granulocytes. 768 28

Reverse transcriptase-polymerase chain reaction showed that interleukin 3, IL-4, IL-5, IL-6, interferon-gamma and stem cell factor mRNA expression were higher in 15-deoxyspergualin-treated spleen cells than in control spleen cells. Increased IL-2 and IFN-gamma mRNA expression were observed in 15-deoxyspergualin-treated bone marrow cells. On the other hand, increased platelet counts in BALB/c-->C3H/He bone marrow chimeras were observed from days 20 to 33 in our previous work, when they were treated with 15-deoxyspergualin from days 14 to 25. In contrast, marked leukocytopenia and anemia were simultaneously observed, although a marked leukocytosis and a rapid recovery of anemia were observed on day 33 and thereafter. To analyze effects of 15-deoxyspergualin on hematopoiesis and the immune system, we examined mRNA expression in bone marrow and spleen cells from BALB/c-->C3H/He bone marrow chimeras treated with 15-deoxyspergualin from days 14 to 25. Reverse transcriptase-polymerase chain reaction showed that IL-3, IL-4, IL-6, stem cell factor, granulocyte colony-stimulating factor, and granulocyte/macrophage colony-stimulating factor mRNA expression were higher in 15-deoxyspergualin-treated chimeras than in control chimeras, indicating that these cytokines are responsible for an enhancement of hematopoiesis. It was conceivable that IL-6 supported thrombopoiesis in concert with other cytokines. On the contrary, increased IFN-gamma, IL-2, IL-3, IL-4, and IL-10 mRNA expression may play an immunosuppressive role in vivo.
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PMID:Effects of 15-deoxyspergualin in vitro and in vivo on cytokine gene expression. 797 17

Within the hematopoietic lineage, the monoclonal antibody (MoAb) CD66 reacts with cells of the granulocyte lineage, but not with the majority of progenitor cells from human bone marrow. Our previous studies have shown that CD66 binds specifically to at least three carcinoembryonic antigen (CEA) superfamily members, ie, CEA itself, nonspecific cross-reacting antigen (NCA), and CGM1, but not to CGM6 (NCA-95). In this report, we show that CD66 will also identify the biliary glycoproteins (BGP). A full-length cDNA for the BGPc molecule (a cytoplasmic splice variant of BGPa) was isolated by expression cloning using the CD66 MoAbs. This protein has an identical extracellular and transmembrane sequence to BGPa with one N-terminal IgV like domain, three IgC-like extracellular domains (A1, B1, and A2), plus a transmembrane domain, but the cytoplasmic domain is spliced by 53 nucleotides. Reverse transcriptase-polymerase chain reaction experiments show that this splice variant can be detected in colonic carcinoma cell lines, in primary colonic adenocarcinomas, and in myeloid and B-cell lines to varying degrees. Quantitative analyses of BGPc RNA expression by RNase protection indicate that abundant levels occur only in the colonic, but not in the hematopoietic, cell lines tested. Studies presented here show that BGPc mediates homotypic adhesion and suggest that the cytoplasmic splicing does not alter the initial homotypic adhesion properties of BGPa.
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PMID:CD66 identifies the biliary glycoprotein (BGP) adhesion molecule: cloning, expression, and adhesion functions of the BGPc splice variant. 801 19

Peripheral lymphoid tissues contain a fibroblastic cell type referred to as stromal cells or reticulum cells which interact with lymphocytes as part of the lymphoid microenvironment. After isolation from human tonsils and expansion in vitro we analyzed the surface phenotype, extracellular matrix components, cytoskeletal products, cytokine production, binding and functional interaction with B lymphocytes of in vitro cultured stromal cells (HTSC) both in resting condition and after activation with tumor necrosis factor (TNF)-alpha and interferon (IFN)-gamma. Our results show that HTSC do not express specific myeloid, lymphoid, endothelial or epithelial markers. HTSC express CD54 (ICAM-1), CD49a (VLA-1), CD49b (VLA-2), CD49c (VLA-3), CD49e (VLA-5), CD49f (VLA-6), CD29, CD51, CD44 and produce vinculin, beta-tubulin, alpha-actin, vimentin, fibronectin, laminin and collagen types I, III and IV. Activation of HTSC up-regulated CD54 (ICAM-1) and induced HLA-DR and CD106 (VCAM-1). HTSC constitutively produce interleukin (IL)-6 which is enhanced upon activation with TNF-alpha. IL-8 and granulocyte/macrophage colony-stimulating factor are detected only in the supernatants of activated HTSC. Reverse transcriptase polymerase chain reaction analysis revealed that HTSC display mRNA for IL-1 alpha, leukemia inhibitory factor and IL-7. The adhesion of tonsillar B lymphocytes to activated HTSC is mediated by CD11a/CD18 and CD54. Furthermore, HTSC can induce maximal proliferation of IL-2-activated B lymphocytes cocultured in direct cell-cell contact with HTSC. These results clearly distinguish in vitro cultured HTSC from common fibroblasts and other non-lymphoid elements present in the lymphoid parenchyma, such as follicular dendritic cells, and show that HTSC actively participate in the lymphoid microenvironment. In vitro cultures of HTSC could therefore be a useful model system for detailed analysis of the interactions between stromal cells and lymphocytes under physiological and pathological conditions.
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PMID:In vitro cultured stromal cells from human tonsils display a distinct phenotype and induce B cell adhesion and proliferation. 856 62

The distribution of myeloid lineage-associated cytokine receptors and lysosomal proteins was analyzed in human CD34+ cord blood cell (CB) subsets at different stages of myeloid commitment by reverse-transcriptase polymerase chain reaction (RT-PCR). The highly specific granulomonocyte-associated lysosomal proteins myeloperoxidase (MPO) and lysozyme (LZ), as well as the transcription factor PU.1, were already detectable in the most immature CD34+Thy-1+ subset. Messenger RNA (mRNA) levels for the granulocyte-colony stimulating factor (G-CSF) receptor, granulocyte-macrophage (GM)-CSF receptor alpha subunit and tumor necrosis factor (TNF) receptors I (p55) and II (p75) were also detected in this subset in addition to c-kit and flt-3, receptors known to be expressed on progenitor cells. By contrast, the monocyte-macrophage colony stimulating factor (M-CSF) receptor was largely absent at this stage and in the CD34+Thy-1-CD45RA- subsets. The M-CSF receptor was first detectable in the myeloid-committed CD34+Thy-l-CD45RA+ subset. All other molecules studied were found to be expressed at this stage of differentiation. Different cocktails of the identified ligands were added to sorted CD34+Thy-1+ single cells. Low proliferative capacity was observed after 1 week in culture in the presence of stem cell factor (SCF) + Flt-3 ligand (FL) + G-CSF. Addition of GM-CSF to this basic cocktail consistently increased the clonogenic capacity of single CD34+Thy-1+ cells, and this effect was further enhanced (up to 72.3 +/- 4.3% on day 7) by the inclusion of TNF-alpha. In conclusion, the presence of myeloid-associated growth factor receptor transcripts in CD34+ CB subsets does not discriminate the various stages of differentiation, with the exception of the M-CSF receptor. In addition, we show that TNF-alpha is a potent costimulatory factor of the very immature CD34+Thy-1+ CB subset.
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PMID:Analysis of myeloid-associated genes in human hematopoietic progenitor cells. 932 52

In response to dibutyryl cyclic AMP (dbcAMP) and all-trans retinoic acid (ATRA), HL60 cells differentiate into granulocyte-like cells. Membrane-associated phospholipase D (PLD) activity in response to guanosine 5'-O-(3-thiotriphosphate) (GTP gamma S) or phorbol myristate acetate (PMA) was upregulated by these treatments. Reverse transcriptase-polymerase chain reaction (RT-PCR) analyses revealed that both hPLD1a and hPLD1b mRNAs were expressed in HL60 cells and that their expression levels increased during differentiation. hPLD2 mRNA levels rose dramatically during differentiation. These results suggest that the PLD genes undergo changes in transcriptional regulation during granulocytic differentiation of HL60 cells.
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PMID:Increased mRNA expression of phospholipase D (PLD) isozymes during granulocytic differentiation of HL60 cells. 951 45


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