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)

The SPOC1 cell, a novel goblet cell line derived from rat trachea, was tested for its ability to exhibit regulated mucin secretion in response to purinergic (P2) agonists. High-molecular mass glycoconjugates (HMMGs) purified by CsCl-density-gradient centrifugation had a buoyant density of 1.45 g/ml. The purified HMMG material exhibited a single major band with an apparent molecular mass of greater than 1000 kDa in SDS/ polyacrylamide gels stained with silver or blotted and stained with soya-bean agglutinin. [3H]HMMG was resistant to proteoglycan-degrading enzymes, but was susceptible to neuraminidase. The HMMG was approx. 91% carbohydrate by weight, and the glycosides were O-linked. The HMMG amino acid composition was enriched in Ser and Thr (sum 27%). Thus SPOC1-cell HMMG possess the characteristics of mucin. Mucin secretion by SPOC1 cells, grown on permeable supports and perfused luminally, was stimulated by ATP, UTP and adenosine 5'-[gamma-thio]triphosphate (100 microM) 4-5-fold over a baseline of 4 ng/min. The three dose-effect relations were nearly identical (K0.5 approximately 4 microM). SPOC1 cells grown on plastic and rat tracheal epithelial primary cells responded similarly to ATP and/or UTP. SPOC1 cells failed to respond to other purinergic agonists, either luminally or serosally, and consequently seem to possess an apical membrane P2u purinoceptor. SPOC1-cell total RNA was probed for P2u purinoceptor mRNA. Using conserved primers for both reverse transcriptase and PCR, a single band of the predicted size was observed, which had a nucleotide base sequence identical with the rat P2u purinoceptor mRNA. Thus SPOC1 cells secrete mucin under the control of a P2u purinoceptor; they should prove useful in dissecting the associated cellular regulatory pathways.
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PMID:P2u purinoceptor regulation of mucin secretion in SPOC1 cells, a goblet cell line from the airways. 867 Jan 74

The stable differentiated human colonic epithelial cell line, HT29-C1.16E, was used to study the effects of interleukin-1 (IL-1) on mucin exocytosis. The main findings include: (a) IL-1 stimulated a rapid release of mucin from filter grown HT29-C1.16E cells, this effect being dose related; (b) this secretory effect was abolished in the presence of the blocking monoclonal antibody M4 specific for IL-1 receptors type I, showing that IL-1 receptors type I mediated IL-1 action; (c) experiments based on chamber cultures showed that these receptors were located on the basolateral membranes of HT29-C1.16E cells; (d) finally, mRNA for IL-1 receptors type I were detected by reverse transcriptase-polymerase chain reaction in these cells. To extend these findings to the in vivo situation, the rapid stimulatory effect of IL-1 on mucin exocytosis may contribute to the wash out of noxious agents during mucosal inflammation.
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PMID:Direct secretory effect of interleukin-1 via type I receptors in human colonic mucous epithelial cells (HT29-C1.16E). 880 Dec 4

The CD24 surface antigen is a small glycophosphatidylinositol (GPI)-anchored glycoprotein found on human granulocytes and most B lymphocytes. Many CD24 monoclonal antibodies (MoAbs) have been described that identify several epitopes, with the majority of them related to carbohydrate structures associated with the CD24 molecule. Considerable variation has been observed in the apparent tissue distribution of the CD24 antigen depending on the MoAb used, and hence the CD24 epitope studied. In this study, CD24 expression by human cell lines and normal hematopoietic call populations was assessed using a panel of carbohydrate and protein core-specific CD24 MoAbs and reverse transcriptase polymerase chain reaction (RT-PCR) analysis. A number of CD24 carbohydrate epitope-reactive MoAbs bound to both T lymphocytes and several hematopoietic cell lines, despite the absence of concomitant CD24 mRNA or detectable surface CD24 core protein in the same cells. This additional CD24 MoAb reactivity on T lymphocytes was, in common with that observed on granulocytes (CD24 protein+), specifically inhibited by the presence of both sialyllactose and mucin. Similarly, the binding of carbohydrate epitops-reactive CD24 MoAb was reduced on both T lymphocytes and granulocytes by pretreatment with phospholipase C, pronase, or neuraminidase. Together, the data indicate that a number of CD24-associated carbohydrate epitopes have a broader tissue distribution than the CD24 protein and are expressed on additional GPI-linked molecule(s). These findings have immediate implications for both leukemia phenotyping and attempts to examine CD24 function with CD24 MoAb.
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PMID:Human T lymphocytes and hematopoietic cell lines express CD24-associated carbohydrate epitopes in the absence of CD24 mRNA or protein. 887 3

The polydispersity of most human secretory mucin messages has made them difficult to detect specifically and quantitatively, impeding the evaluation of the relative expression of the various mucin genes and their role in normal and pathological conditions. For this reason, we developed competitive reverse transcriptase-polymerase chain reaction (PCR) methods to measure the airway mucins MUC2 and MUC5AC. Oligonucleotide pairs were designed that specifically detect MUC2 and MUC5AC, as demonstrated by the size and sequence of the PCR product and the expected tissue distribution. The mucin oligonucleotide primers were used to synthesize internal competitive standards, called MIMIC. Using this assay, the relative expression of these messages was analyzed in retinoid-replete or -deprived cultures of normal human tracheobronchial epithelial (NHTBE) cells. Retinoid deficiency induces squamous metaplasia in vivo and in vitro. Consistent with these observations and in contrast to a previous report, retinoid-deprived cultures produced at least an order of magnitude less MUC2 and MUC5AC message than retinoid-replete cultures. In summary, this paper describes methodology that can be applied to the specific and quantitative measurement of mucin messages and demonstrates that, in NHTBE cells, the level of MUC2 and MUC5AC mRNA is increased by retinoids.
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PMID:Quantitation of mucin RNA by PCR reveals induction of both MUC2 and MUC5AC mRNA levels by retinoids. 899 74

Human saliva contains high and low molecular weight mucin glycoproteins, that are distinct. Recently the gene encoding low molecular weight salivary mucin was cloned and designated MUC7, whereas the primary structure of high molecular weight salivary mucin is unclear. Furthermore, the expression patterns of high and low molecular weight salivary mucins in salivary glands have been debated. We have previously generated monoclonal antibodies specific for the peptide cores of salivary mucins. In the present study a monoclonal antibody specific for high molecular weight salivary mucin was used to screen a human salivary gland cDNA library. A single clone, SAL1, was identified and found to be encoded by tracheobronchial mucin gene MUC5B. A previously reported partial cDNA sequence from salivary mucin was linked to SAL1/MUC5B by genomic cloning and reverse transcriptase-polymerase chain reaction. Northern analysis of salivary gland RNA probed with SAL1 suggested that MUC5B was highly expressed in salivary glands. In situ hybridization was performed with a SAL1/MUC5B probe and a MUC7 probe. All mucous cells from the submandibular, sublingual, palatine, and labial glands labeled with the MUC5B probe, while serous cells labeled with the MUC7 probe. These findings were in accordance with our previous immunohistological results of the cellular localizations of salivary mucins. The results suggest that MUC5B is identical to or a major fraction of high molecular weight salivary mucin, and that MUC5B is expressed in all mucous cells of salivary glands. In contrast MUC7 is expressed in serous cells of salivary glands except the parotid glands.
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PMID:Identification of a major human high molecular weight salivary mucin (MG1) as tracheobronchial mucin MUC5B. 914 51

CD43 (leukosialin, sialophorin), a cell-surface associated mucin that is constitutively expressed at high levels on most leukocytes, is thought to be involved in cell activation and adhesion. We here provide evidence that the vitamin A metabolites all-trans and 13-cis retinoic acid up-regulate CD43 on human leukemic (HMC-1) mast cells, as determined by flow cytometry, Western blot analysis, and by semiquantitative reverse transcriptase-polymerase chain reaction. Enhanced CD43 expression was accompanied by a strong increase in anti-CD43-mediated, LFA-1-dependent homotypic aggregation of HMC-1 cells, demonstrating that newly synthesized CD43 is functionally active in transmitting signals across the plasma membrane which result in enhanced cellular adhesion. CD43 expression was also enhanced in response to retinoic acids on isolated human skin mast cells and human monocytes, but not on cells of the basophilic cell line KU-812 and promyelocytic HL-60 cells, indicating that these agents might act in a cell-type specific manner. These combined result-point to a novel aspect in the regulation of CD43. Possibly, vitamin A metabolites act directly on the CD43 gene, since putative retinoic acid response elements have been detected within its regulatory regions.
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PMID:CD43 (leukosialin, sialophorin) expression is differentially regulated by retinoic acids. 917 4

Mucins, including MUC-1, are generally considered to be products of epithelial tissues and of their tumors. To examine the possible expression of MUC-1 in other cell types, a panel of human epithelial and non-epithelial tumor cell lines was studied by reverse transcriptase polymerase chain reaction (RT-PCR), Northern blot analysis, immunocytology and radioimmunoprecipitation. Using the highly sensitive RT-PCR method, products corresponding to the non-repetitive 5' and 3' MUC-1 sequences were detected in all the cell lines examined. Amplified products lacking the tandem repeat region of MUC-1, including a new short form (designated MUC-1/Z) different from the previously reported MUC-1/Y protein, were also detected in most cell lines tested. Northern blot analysis, using a probe to the variable number tandem repeat (VNTR) region, confirmed the presence of MUC-1 mRNA in the astrocytoma, melanoma and neuroblastoma cell lines studied. MUC-1 protein was detected by immunocytology in these cell lines using monoclonal antibody (MAb) 139H2. Immunoprecipitation analysis with [3H]-glucosamine-labeled cell lysates and MAb 139H2 or an antibody to the cytoplasmic domain, CT-1, detected MUC-1 protein in 2 epithelial cell lines, an astrocytoma cell line (SK-MG-4) but not in the melanoma and neuroblastoma cell lines studied. Northern blot analysis using a probe to the 3' end of MUC-1 mRNA, confirmed the presence of MUC-1 mucin and also identified short products corresponding to the size of the short variant forms. Protein products corresponding to the MUC-1/Y and MUC-1/Z variant forms were not observed using either [3H]-glucosamine-labeled OVCAR-3 cells or [3H]-amino acid-labeled MCF-7 cells and either CT-1 antibody or MAb 232A1, detecting an epitope to the C-terminal region. Thus, depending on the sensitivity of the assay used, varying amounts of MUC-1 mRNA and protein could be detected in non-epithelial tumor cell lines. Although the amounts of MUC-1 in these cell lines are much lower than in carcinomas, it is possible that MUC-1 mucin serves a similar function in non-epithelial as in epithelial cells. The possible role of MUC-1/Y and MUC-1/Z variant forms in these cell lines is not understood.
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PMID:Comparison of MUC-1 mucin expression in epithelial and non-epithelial cancer cell lines and demonstration of a new short variant form (MUC-1/Z). 921 28

Trefoil polypeptides are expressed mainly in the amphibian skin and the gastrointestinal tract of mammals, usually coexpressed with mucin-glycoproteins. Recently, the trefoil polypeptides were shown to be expressed also in different areas of the human and murine brain. To investigate the expression and possible functions of ITF in rat pheochromocytoma (PC12) cells were employed. PC12 cells show a low basal expression of this polypeptide as determined by reverse transcriptase-polymerase chain reaction. After treatment with the synthetic glucocorticoid dexamethasone, the second messenger cyclic adenosine monophosphate and the neurotrophic factor nerve growth factor the expression of the trefoil polypeptide ITF was increased as shown by reverse transcriptase-polymerase chain reaction and by immunocytochemistry. Since these various stimuli can directly can directly alter the expression level of this peptide we conclude that the presented results may from the basis for further investigations of possible functions of this novel gut-brain polypeptide in neurons using PC12 cells.
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PMID:Expression of the trefoil polypeptide ITF in PC12 cells. 923 42

Airway goblet cells secrete mucin in response to ATP and uridine 5'-triphosphate (UTP), but the underlying signal transduction pathways are poorly understood. Cultures of SPOC1 cells (L. H. Abdullah, S. W. Davis, L. Burch, M. Yamauchi, S. H. Randell, P. Nettesheim, and C. W. Davis. Biochem. J. 316: 943-951, 1996) secreted mucin on exposure to phorbol 12-myristate 13-acetate (PMA) [apparent affinity (K0.5) approximately 100 nM] and ionomycin (K0.5 approximately 5 microM) almost fivefold over baseline. Thapsigargin also elicited secretion (K0.5 approximately 20 nM). Ionomycin and PMA together elicited approximately twice the secretion of either agent alone. Overnight exposure to half-maximal PMA abolished the response to maximal doses of UTP and PMA, whereas ionomycin was fully effective. Protein kinase C (PKC) activity in the membrane fraction was increased by maximal doses of PMA and UTP, whereas ionomycin had no effect. PKC inhibitors were relatively ineffective against PMA- and UTP-induced mucin secretion. Human and canine goblet cells in epithelial explants, by video microscopy, underwent exocytosis with ionomycin (1 microM) and PMA (0.1 or 1 microM). SPOC1 cell mucin secretion was not stimulated by forskolin, 8-(4-chlorophenylthio)-adenosine 3',5'-cyclic monophosphate, or 8-bromoguanosine 3',5'-cyclic monophosphate. Cystic fibrosis transmembrane conductance regulator was not detected in SPOC1 cells by Western blotting, and its mRNA was detected by reverse transcriptase polymerase chain reaction (PCR) only as a very weak band and after 55 PCR cycles. Multidrug resistance (MDR1), however, was readily detected by Western blotting, and its mRNA was detected as a major band after 35 PCR cycles. Thus airway goblet cell mucin secretion, distal to receptor activation, may be regulated independently by Ca(2+)- and PKC-dependent pathways. Cystic fibrosis transmembrane conductance regulator and cyclic nucleotides, however, may not play a major role in this secretion.
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PMID:Protein kinase C and Ca2+ activation of mucin secretion in airway goblet cells. 925 57

Mucinous carcinomas of the colorectum have been reported to overexpress the intestinal mucin MUC2. The purpose of this study was to determine whether this alteration is shared by mucinous tumours of the ovary, breast, and pancreas. A total of 40 breast carcinomas (22 of mucinous and 18 of ductal invasive type), 39 ovarian adenocarcinomas (16 mucinous, 23 serous), 47 colorectal carcinomas (25 mucinous and 22 non-mucinous), and 41 pancreatic adenocarcinomas (14 mucinous, 27 non-mucinous) were investigated by immunohistochemistry with the anti-MUC2 monoclonal antibody 4F1 and the expression pattern was ranked. MUC2 mucin is expressed in the normal colonic epithelium; in the normal epithelium of the breast, ovary, and pancreas, it was not detectable by immunohistochemistry or by reverse transcriptase-polymerase chain reaction (RT-PCR). In agreement with previous reports, the colonic mucinous carcinomas differed significantly from the non-mucinous carcinomas by strong MUC2 expression. In all mucinous carcinomas of the ovary, breast, and pancreas, de novo expression of the MUC2 gene was observed, which differentiated mucinous and non-mucinous carcinomas of these tissues (P < 0.001). The overexpression or ectopic expression of the MUC2 gene exhibited by mucinous carcinomas of four organs indicates a common genetic lesion associated with the mucinous tumour phenotype.
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PMID:Overexpression or ectopic expression of MUC2 is the common property of mucinous carcinomas of the colon, pancreas, breast, and ovary. 930 58


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