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)

Lectins on antigen presenting cells are potentially involved in the antigen uptake and the cellular recognition and trafficking. Serial analysis of gene expression in monocyte-derived dendritic cells (DCs), monocytes, and macrophages revealed that 7 of the 19 C-type lectin mRNA were present in immature DCs. Two of these, the macrophage mannose receptor and the macrophage lectin specific for galactose/N-acetylgalactosamine (MGL), were found only in immature DCs, as confirmed by reverse transcriptase-PCR and flow cytometric analysis. By subcloning and sequencing the amplified mRNA, we obtained nucleotide sequences encoding seven different human MGL (hMGL) subtypes, which were apparently derived from alternatively spliced mRNA. In addition, the hMGL gene locus on human chromosome 17p13 contains one gene. A single nucleotide polymorphism was identified at a position in exon 3 that corresponds to the cytoplasmic region proximal to the transmembrane domain. Of all the splicing variants, the hMGL variant 6C was expressed at the highest levels on immature DCs from all donors tested. Immature DCs could incorporate alpha-GalNAc-modified soluble acrylamide polymers, and this was significantly inhibited by pretreatment of the cells with an anti-hMGL monoclonal antibody that blocks the lectin-carbohydrate interaction. We propose that hMGL is a marker of imDCs and that it functions as an endocytic receptor for glycosylated antigens.
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PMID:The macrophage C-type lectin specific for galactose/N-acetylgalactosamine is an endocytic receptor expressed on monocyte-derived immature dendritic cells. 1191 1

We have used a rat model of focal cerebral ischemia to investigate changes in gene expression that occur during stroke. To monitor these changes, we employed representational difference analysis-polymerase chain reaction (PCR). A total of 128 unique gene fragments were isolated, and we selected 13 of these for quantitative reverse transcriptase-PCR analysis. Of these 13 genes, we found seven that were differentially expressed. Four of these genes have not previously been implicated in stroke, and include neuronal activity regulated pentraxin (Narp), cysteine rich protein 61 (Cyr61), Bcl-2 binding protein BIS (Bcl-2-interacting death suppressor), and lectin-like ox-LDL receptor (LOX-1). We demonstrated differential expression of each gene by quantitative PCR analysis, and in the case of LOX-1, we further confirmed differential expression by in situ hybridization. LOX-1 expression is induced greater than ten fold at the core lesion site, and is essentially localized to the ipsilateral half of the brain. LOX-1 appears to be expressed in a non-neuronal cell type, and it does not appear to be expressed in vascular endothelial cells within the brain. This suggests that LOX-1 may serve a novel function in the brain.
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PMID:Identification of differentially expressed genes induced by transient ischemic stroke. 1200 27

Recent studies on dendritic cell (DC)-associated genes have been performed using monocyte-derived DCs (MoDCs) in different maturation stages. In our approach, to uncover the novel DC-associated genes and their expression profiles among the different DC subsets, we constructed a subtracted DC-cDNA library from CD1a(+), CD14(+), and CD11c(-) DCs by subtracting the genes shared with T cells, B cells, and monocytes, and we then screened the libraries with the aid of microarray technique. The genes showing remarkable specificity to DCs in the microarray analysis were selected and confirmed by semiquantitative reverse transcriptase-polymerase chain reaction. Our investigations revealed the following: (1) Genes highly expressed in myeloid DCs are those involved in antigen uptake/processing/presentation, cell metamorphosis, or chemotaxis. (2) Most of the genes previously identified in MoDCs, such as TARC, ferritin L-chain, lysosomal acid lipase, alpha- and beta-tubulin, osteopontin (Eta-1), and others, are not markedly expressed in CD11c(-) DCs regardless of their maturation status. On the other hand, specific transcription factors and MHC class II molecules, such as interferon regulatory factor-4 (IRF4) and HLA-DR, are similarly expressed in both DC subsets. (3) CD14(+) DCs retain unique features of tissue DCs, as evidenced by the gene expression profile of "no CCR7 but more CCR1" and "no TARC but abundant MCP1 and Eta-1." (4) The genes for immunoglobulin (Ig) superfamily Z39Ig, CD20-like precursor, glycoprotein NMB (GPNMB), transforming growth factorbeta (TGF-beta)-induced protein (TGFBI), myeloid DAP12-associated lectin (MDL-1), and 6 novel genes are newly identified as being associated with the phenotypic expression of the DC subsets. These identifications provide important molecular information for further functional studies of the DC subsets.
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PMID:Identification of the genes differentially expressed in human dendritic cell subsets by cDNA subtraction and microarray analysis. 1217 96

Brain tumor formation and growth is accompanied by the proliferation and infiltration of blood capillaries. The phenotypes of endothelial cells that make up capillaries are known to differ not only in the tissues in which endothelial cells are located but also as a result of the microenvironment to which they are exposed. For this reason, primary cultures of brain endothelial cells were isolated from human brain tumors removed by surgery and compared with cells from normal tissue. The primary confluent monolayers that grew out of isolated capillary fragments consisted of closely associated, elongated, fusiform-shaped cells. But brain tumor-derived endothelial cells in culture exhibited significantly less expression of endothelial-specific Factor VIII-related antigen compared with cells isolated from normal tissue. Cultured cells that exhibited binding of Ulex europaeus lectin were shown to take up Dil-Ac-Ldl and formed continuous monolayers that were joined together by tight junctions. The cells also exhibited characteristics of the cells of the brain microvasculature in vitro as seen by the presence of large numbers of mitochondria and few pinocytotic vesicles and by the absence of Weibel-Palade bodies within the cells. The expression of vascular cell adhesion molecule-1, E-Selectin, and the tight junction associated protein ZO-1 but not intercellular adhesion molecule-1 was demonstrated by immunohistological staining or reverse transcriptase-polymerase chain reaction methodologies. Comparative studies of these endothelial cells with endothelial cells from normal tissue will be useful for determining and understanding how the blood-brain barrier differs and functions in tumor and healthy tissues and may lead to strategies for brain tumor therapeutic approaches.
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PMID:Isolation and molecular characterization of brain microvascular endothelial cells from human brain tumors. 1241 24

A lectin, with a molecular mass of approximately 60 kDa and two different subunits exhibiting an N-terminal sequence manifesting considerable homology to phytohemagglutinin from Phaseolus species, was isolated from the ground bean (Vigna sesquipedalis cv ground bean). The lectin was unique in hemagglutinating activity was inhibited by polygalacturonic acid and not by galacturonic acid and other simple monosaccharides. The lectin was isolated by affinity chromatography on Affi-gel blue gel, ion exchange chromatography by fast protein liquid chromatography (FPLC) on Mono S, and gel filtration by FPLC on Superdex 75. It was adsorbed on both Affi-gel blue gel and Mono S. Ground bean lectin exhibited mitogenic activity on murine splenocytes with the maximal response achieved at a concentration of 156 nM, as similar to the dose required for Con A. The viability of hepatoma (HepG2), leukemia (L1210), and leukemia (M1) cells was reduced in the presence of ground bean lectin, which also exerted an inhibitory activity toward HIV-1 reverse transcriptase IC(50) of 73 microM. The hemagglutinating activity of the lectin was unaffected by trypsinization and the presence of a number of divalent cations, but was augmented by 500 mM K(+) ions. The activity was unstable above 40 degrees C although some activity remained after heating and at 100 degrees C for 30s.
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PMID:Purification of a trypsin-stable lectin with antiproliferative and HIV-1 reverse transcriptase inhibitory activity. 1256 97

Polyploidy is characterized by a greater than diploid content of DNA in a cell. Previous measurements of ploidy level in different organs of humans and rodents, including the aorta, indicated an increase in old versus young. We hypothesized that aortic vascular smooth muscle polyploidy is a biomarker for aging and that the augmented DNA dosage affects selective gene-specific transcript expression. Our results demonstrate that tetraploidy increases exponentially over the life span of the animal, serving as an indicator of age. Approximately 60% of the vascular smooth muscle cells in the thoracic aorta of 36-month-old Brown Norway rats are tetraploid compared with 8% in their 3-month-old counterparts. Microarray analysis and reverse transcriptase-PCR was performed with mRNA isolated from sorted diploid (2N) and tetraploid (4N) vascular smooth muscle cells from old rats to identify differentially expressed transcripts. For the majority of detectable transcripts, an increase in DNA content led to a proportional increase in mRNA. A select group of transcripts, however, were reduced in tetraploid compared with diploid cells. These mRNAs correspond to guanine deaminase, to the matrix proteins rat glypican 3 (OCI-5) and decorin, as well as to the inflammation-associated transcripts, insulin-like growth factor-binding protein 6, macrophage inflammatory protein 2 precursor, macrophage galactose N-acetylgalactoseamine-specific lectin, and complement component C4. Our study is the first to describe aortic ploidy level as a biomarker for aging and to indicate that changes associated with increased DNA content per cell may selectively suppress the expression of specific genes.
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PMID:Vascular smooth muscle polyploidization as a biomarker for aging and its impact on differential gene expression. 1463 4

A novel antifungal protein, designated castamollin, was isolated from Chinese chestnut (Castanea mollisima) seeds with a procedure involving ion exchange chromatography on DEAE-cellulose, affinity chromatography on Affi-gel blue gel, ion exchange chromatography on CM-Sepharose and FPLC-gel filtration on Superdex 75. Castamollin possessed a novel N-terminal sequence demonstrating little similarity to N-terminal sequences of Castanea sativa chitinase. Castamollin exhibited a molecular mass of 37kDa in gel filtration and SDS-PAGE. It inhibited the activity of human immunodeficiency virus-1 reverse transcriptase with an IC(50) of 7microM and translation in a cell-free rabbit reticulocyte lysate system with an IC(50) of 2.7microM. Castamollin displayed antifungal activity against Botrytis cinerea, Mycosphaerella arachidicola, Physalospora piricola, and Coprinus comatus but was devoid of lectin activity.
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PMID:Purification of castamollin, a novel antifungal protein from Chinese chestnuts. 1468 Sep 38

The proteoglycans aggrecan, versican, neurocan, and brevican bind hyaluronan through their N-terminal G1 domains, and other extracellular matrix proteins through the C-type lectin repeat in their C-terminal G3 domains. Here we identify tenascin-C as a ligand for the lectins of all these proteoglycans and map the binding site on the tenascin molecule to fibronectin type III repeats, which corresponds to the proteoglycan lectin-binding site on tenascin-R. In the G3 domain, the C-type lectin is flanked by epidermal growth factor (EGF) repeats and a complement regulatory protein-like motif. In aggrecan, these are subject to alternative splicing. To investigate if these flanking modules affect the C-type lectin ligand interactions, we produced recombinant proteins corresponding to aggrecan G3 splice variants. The G3 variant proteins containing the C-type lectin showed different affinities for various ligands, including tenascin-C, tenascin-R, fibulin-1, and fibulin-2. The presence of an EGF motif enhanced the affinity of interaction, and in particular the splice variant containing both EGF motifs had significantly higher affinity for ligands, such as tenascin-R and fibulin-2. The mRNA for this splice variant was shown by reverse transcriptase-PCR to be expressed in human chondrocytes. Our findings suggest that alternative splicing in the aggrecan G3 domain may be a mechanism for modulating interactions and extracellular matrix assembly.
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PMID:Alternative splicing in the aggrecan G3 domain influences binding interactions with tenascin-C and other extracellular matrix proteins. 1472 76

An 18-kDa lectin, with an N-terminal sequence displaying slight similarity to some lectins and fungal immunomodulatory proteins, was isolated from the mushroom Ganoderma capense (Lloyd) Teng. It exhibited more potent mitogenic activity than that of concanavalin A toward mouse splenocytes, and antiproliferative activity toward leukemia (L1210 and M1) cells and hepatoma (HepG2) cells. The isolation procedure entailed ion exchange chromatography on Q-Sepharose, fast protein liquid chromatography (FPLC)-ion exchange chromatography on Mono S, and FPLC-gel filtration on Superdex 75. D(+)-galactose and D(+)-galactosamine specifically inhibited the hemagglutinating activity of the lectin. The hemagglutinating activity of the lectin was not affected over the temperature range 0-100 degrees C and after exposure to 100 degrees C for 60min. The activity was stable in the pH range of 4-11, and after incubation with solutions of various chlorides (from 3.125 to 50mM) including NaCl, KCl, CaCl(2), MgCl(2), ZnCl(2), MnCl(2), and AlCl(3). However, it was potentiated by 12.5-50mM FeCl(3). The lectin was devoid of HIV-1 reverse transcriptase inhibitory and antifungal activities.
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PMID:A mushroom (Ganoderma capense) lectin with spectacular thermostability, potent mitogenic activity on splenocytes, and antiproliferative activity toward tumor cells. 1475 Dec 30

The impact of a pathogen-induced inflammatory response on dendritic cells (DCs) and on their expression of galectin-3 (Gal-3) was studied on splenic DCs (sDCs) from Trypanosoma cruzi-infected mice. We determined the lectin expression and also presentation of ligands using the labeled galectin as probe. By reverse transcriptase polymerase chain reaction, western blot analysis, quantitative glycocytochemistry, and computer-assisted quantitative microscopy, we demonstrate that, in sDCs from infected mice, expression of Gal-3 and Gal-3-specific ligands were markedly up-regulated and adhesiveness was increased with Gal-3-coated substratum. Gal-3 expression was also enhanced in T. cruzi-infected D2SC-1 cells. To assess influence on migration, we had to work exclusively with D2SC-1 cells because sDCs rapidly lost their capacity to adhere to substratum. Migration of infected- and TCM-treated D2SC-1 cells were reduced when substratum was coated with Gal-3. Expression of Gal-3 by D2SC-1 was reduced when they were incubated with anti-Gal-3 antisense oligonucleotide without effect on cell invasion by the parasite. By using seven neoglycoconjugates, we probed the cellular capacity to specifically bind carbohydrate ligands. Similar to Gal-3, an up-regulation was noted with respect to sites specific for Man and alpha-GalNAc, respectively, revealing that infection-dependent changes are not confined to Gal-3-dependent parameters. Considered together, these data document for the first time that a parasitic infection can modulate both in vivo and in vitro the expression of Gal-3 and of ligands for this lectin in DCs with functional consequences on their capacities of adhesion and migration. These results suggest a new immunomodulatory property of T. cruzi.
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PMID:Up-regulation of galectin-3 and its ligands by Trypanosoma cruzi infection with modulation of adhesion and migration of murine dendritic cells. 1504 84


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