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:2.4.99.7 (sialyltransferase)
1,534 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

We have assayed glycosyltransferase activities during the granulocytic and macrophage-like differentiation of human promyelocytic leukemia (HL-60) cells. Functional granulocytic differentiation was assayed by the decarboxylation of 2-deoxyglucose in addition to nitroblue tetrazolium reduction. Dimethylsulfoxide (DMSO) treated HL-60 cells, induced to granulocytic differentiation, had higher 2-deoxy-glucose decarboxylation activity, and contained less sialyltransferase (ST), more fucosyltransferase (FT), and more N-acetylglucosaminyltransferase (NGT) activities than untreated cells. HL-60 cells treated with another granulocytic differentiator, retinoic acid, also had higher 2-deoxyglucose decarboxylation activity, and contained less ST, more FT, and more NGT activities than untreated cells. In contrast, cells treated with 12-O-tetradecanoyl-phorbol-13-acetate (TPA) reported to differentiate HL-60 to macrophage-like cells, but did not show an increased level of 2-deoxyglucose decarboxylation activity, but contained more galactosyltransferase (GT) and FT activities as compared to untreated cells. These findings suggest that the alterations of glycosyltransferase levels during the differentiation of precursor cells may not depend upon different inducers, but are characteristic of the phenotypic expression of the mature cell type.
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PMID:Glycosyltransferase alterations are cell type related when human promyelocytic leukemia (HL-60) cells are treated with various inducers of differentiation. 641 38

The mononuclear cells separated from human blood by Ficoll-Hypaque centrifugation contained and released sialyltransferase, galactosyltransferase, and fucosyltransferase. Granulocytes contained and released lesser amounts of glycosyltransferases, whereas platelets released more fucosyltransferase than sialyltransferase or galactosyltransferase. When mononuclear cells were incubated with 12-O-tetradecanoyl-phorbol-13-acetate (TPA), the release of these three glycosyltransferases increased two- to six-fold, and cell suspension glycosyltransferase activities decreased 10-50%. Mononuclear cells were fractionated into lymphocytes and monocytes using baby hamster kidney cells microexudate-coated flasks. TPA stimulated the release of glycosyltransferases from lymphocytes but not from monocytes. The release of glycosyltransferases by TPA-treated mononuclear cells was not further stimulated by reincubation with TPA and was not affected by puromycin, cAMP, or cGMP. Concanavalin A, a mitogenic stimulator of lymphocytes, also stimulated the release of glycosyltransferases from mononuclear cells, but to a lesser extent. TPA did not stimulate the release of 5'-nucleotidase or decrease its activity on the cell pellet. Triton X-100 (0.2%) stimulated the release of glycosyltransferases to the same extent as TPA, but also caused the release of 5'-nucleotidase. [(3)H]TPA bound specifically and reversibly to mononuclear cells. The possible relationship between glycosyltransferase release and TPA effect on the plasma membrane is discussed.
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PMID:12-O-tetradecanoyl-phorbol-13-acetate release of glycosyltransferases from human blood cells. 644 9

Retinoic acid inhibits the proliferation of the murine melanoma clone S91-C-2 cells, enhances the glycosylation of specific cell surface sialoglycoproteins, and stimulates sialytransferase activity. Mutant clones, selected from the S91-C-2 cells for resistance to the growth-inhibitory effect of retinoic acid, were used to explore whether cell surface modulation by retinoic acid is related to growth inhibition. Glycoprotein synthesis was assessed by analysis of [3H]glucosamine incorporation into glycoconjugates, and cell surface sialo- and galactoglycoproteins were analyzed after radiolabeling by the NaIO4:NaB3H4 and the neuraminidase plus galactose oxidase:NaB3H4 methods, respectively. The cells were solubilized and the labeled molecules were separated by polyacrylamide gel electrophoresis and identified by fluorography. Sialytransferase activity was measured in detergent-solubilized cells, using cytidine 5' -monophosphate-[14C]sialic acid as a sugar donor and asialofetuin as an exogenous acceptor. The results demonstrated that retinoic acid enhanced [3H]glucosamine incorporation into a Mr 160,000 glycoprotein in the S91-C-2 cells but not in any of the resistant mutant clones, while the pattern of [35S]methionine-labeled proteins was not modified in either the sensitive or the resistant clones. Radiolabeling of a Mr 160,000 sialoglycoprotein on the surface of S91-C-2 and of several retinoic acid-sensitive subclones of S91-C-2 was augmented by retinoic acid. A considerably smaller effect was observed on the labeling of Mr 160,000 sialoglycoprotein on one of the resistant clones, and no significant effect could be detected on the other resistant mutant clones. Sialytransferase activity was increased 2- to 3-fold by retinoic acid in the S91-C-2 cells and in several sensitive subclones, but not in any of the resistant mutant clones. Tetradecanoylphorbol acetate, which inhibits the proliferation of both retinoic acid-sensitive and retinoic acid-resistant cells, failed to increase either sialyltransferase activity or cell surface labeling of sialoglycoproteins. These findings suggest that the ability of retinoic acid to stimulate sialyltransferase activity and glycosylation of cell surface glycoproteins is related to the growth-inhibitory effect of this compound.
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PMID:Correlation of retinoic acid-enhanced sialyltransferase activity and glycosylation of specific cell surface sialoglycoproteins with growth inhibition in a murine melanoma cell system. 649 40

The level of sialyltransferase activity in leukaemic blasts from acute lymphoblastic leukaemia (ALL) cases was significantly lower (3.29 +/- 2.09 pmoles/5 X 10(7) cells or 1.77 +/- 1.16 pmoles/mg protein) than those (18.80 +/- 4.91 pmoles/5 X 10(7) cells or 7.72 +/- 1.75 pmoles/mg protein) of mature lymphocytes from normal volunteers (T less than 0.001). An inverse relationship between the level of sialyltransferase activity and the level of terminal transferase (TdT)activity was seen in blasts from eight TdT-positive ALL cases. No significant difference was observed in the level of sialyltransferase activity between ALL and cells of chronic myelogenous leukemia (CML) in blast crisis. Short Term culture of ALL blast cells with 12-0-tetradecanoylphorbol-13-acetate (TPA) at the concentration of 10-(6)M to 10-(9)M caused a marked increase in sialyltransferase activity. In one of these three ALL cases the population of TdT-positive cells and the TdT activity of the blasts decreased significantly after culture with TPA. These results suggest that biochemical differentiation of leukaemic lymphoblasts has been induced by the addition of TPA, although morphological changes were not observed. Sialyltransferase activity may be a useful indicator for the analysis of differentiation of lymphocytes.
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PMID:Sialyltransferase activity as a marker for the differentiation of lymphocytes. Increase in sialyltransferase activity of blasts from acute lymphoblastic leukaemia cases by 12-o-tetradecanoylphorbol-13-acetate (TPA). 695 64

Higher level of terminal deoxynucleotidyl transferase (TdT) and peanut agglutinin (PNA)-positive cells were found in those fractions of albumin gradient separated rat thymocytes that had a higher level of glucocorticoid (GC) receptors and a lower level of sialyltransferase (S-T) activity. Incubation of thymocytes in these fractions with dexamethasone inhibited RNA synthesis significantly. Incubation of these thymocytes with tetradecanoylphorbol-acetate (TPA) reduced TdT activity, while increasing S-T activity. The higher level of GC receptors may be responsible for GC sensitivity of TdT-positive thymocytes. In addition, sialyltransferase may be a biochemical marker for thymocyte differentiation.
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PMID:Terminal deoxynucleotidyl transferase and glucocorticoid receptors in rat thymocytes. 811 29

Culture of two lymphoid leukemia cell lines with 5 x 10(-9) to 10(-7) M 12-0-tetradecanoyl-phorbol 13-acetate (TPA) induced the significant increase in sialyltransferase, acid phosphatase and butyrate esterase activities, the decrease in poly(A) polymerase and terminal deoxynucleotidyl transferase (TdT) activities. B4-, J5-, TdT- or PNA-positive cells were decreased in TPA-treated cells, while B1-positive cells were increased. These results suggest enzymatic changes as an aspect of TPA-induced differentiation in lymphoid leukemia cell lines. These enzymatic activities may be useful markers for the differentiation of lymphoid leukemia cells.
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PMID:12-0-Tetradecanoylphorbol 13-acetate (TPA)-induced enzymatic change of human non-T, non-B lymphoid leukemia cell lines. 824 98

We have developed a system that recreates in vitro the generation of post-Golgi vesicles from an isolated Golgi fraction prepared from vesicular stomatitis virus- or influenza virus-infected Madin-Darby canine kidney or HepG2 cells. In this system, vesicle generation is temperature- and ATP-dependent and requires a supply of cytosolic proteins, including an N-ethylmaleimide-sensitive factor distinct from NSF. Cytosolic proteins obtained from yeast were as effective as mammalian cytosolic proteins in supporting vesicle formation and had the same requirements. The vesicles produced (50-80 nm in diameter) are depleted of the trans Golgi marker sialyltransferase, contain the viral glycoprotein molecules with their cytoplasmic tails exposed, and do not show an easily recognizable protein coat. Vesicle generation was inhibited by brefeldin A, which indicates that it requires the activation of an Arf-like GTP-binding protein that promotes assembly of a vesicle coat. Vesicles formed in the presence of the nonhydrolyzable GTP analogue guanosine 5'-3-O-(thio)triphosphate retained a nonclathrin protein coat resembling that of COP-coated vesicles, and sedimented more rapidly in a sucrose gradient than the uncoated ones generated in its absence. This indicates that GTP hydrolysis is not required for vesicle generation but that it is for vesicle uncoating. The activity of a Golgi-associated protein kinase C (PKC) was found to be necessary for the release of post-Golgi vesicles, as indicated by the capacity of a variety of inhibitors and antibodies to PKC to suppress it, as well as by the stimulatory effect of the PKC activator 12-O-tetradecanoylphorbol-13-acetate.
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PMID:The in vitro generation of post-Golgi vesicles carrying viral envelope glycoproteins requires an ARF-like GTP-binding protein and a protein kinase C associated with the Golgi apparatus. 866 71

In the framework of a project aimed at the elucidation of the nature of the functional importance of the N-glycosylation of the alpha-subunit of the glycoprotein hormones human lutropin and human chorionic gonadotropin, the structural element alpha-Neu p5Ac-(2-->6)-beta-D-GalpNac-(1-->4)- beta-D-GlcpNAc-(1-->2)-alpha-D-Manp, which is part of the carbohydrate chains of human lutropin, has been prepared by chemical and chemo-enzymatic synthesis in the form of its propyl glycoside. Condensation of 4-O- acetyl-3,6-di-O-benzyl-2-deoxy-2-phthalimido-alpha/beta-D-glucopyranosyl trichloroacetimidate with allyl 3,4,6-tri-O-benzyl-alpha-D-mannopyranoside gave after deacetylation allyl (3,6-di-O-benzyl-2-deoxy-2-phthalimido-beta-D-glucopyranosyl) -(1-->2)-3,4,6-tri-O-benzyl-alpha-D-mannopyranoside. Ethyl 3-O-benzyl-2-deoxy-2-phthalimido-l-thio-beta-D-glucopyranoside was converted into the galacto-derivative ethyl 4,6-di-O-acetyl-3-O-benzyl-2-deoxy-2-phthalimido-1-thio-beta-D -galactopyranoside via an oxidation-reduction route, as well as via SN2-type substitution with acetate. The use of this galacto thioglycoside, after its conversion into the corresponding bromide, as GaIN donor for condensation with the mentioned disaccharide derivative yielded after deacetylation allyl (3-O-benzyl-2-deoxy-2-phthalimido-beta-D-galactopyranosyl)-(1-->4) -(3,6-di-O-benzyl-2-deoxy-2-phthalimido-beta-D-glucopyranosyl)-(1-->2) -3,4,6-tri-O-benzyl-alpha-D-mannopyranoside. Methylsulfenyl bromide-silver triflate promoted sialylation of this trisaccharide derivative with O-ethyl S-[methyl (5-acetamido-4,7,8,9-tetra-O-acetyl-3,5-dideoxy-D -glycero-alpha-D-galacto-non-2-ulopyranosyl)onate] dithiocarbonate and subsequent deprotection resulted into the aimed tetrasaccharide structural element. Alternatively, this compound was prepared via a block synthesis, which, however, was not superior to the linear strategy. Finally, a stereose lective sialylation of synthetically prepared beta-D-GalpNAc-(1-->4)-beta-D-GlcpNAc-(1-->2)-alpha-D-Manp-(1-->O) CH2CH2CH3 with CMP-Neu5Ac and rat liver alpha-2,6-sialyltransferase was accomplished affording the same tetrasaccharide structural element.
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PMID:Chemical and chemo-enzymatic synthesis of the alpha-Neu p5Ac-(2-->6)- beta-D-GalpNAc-(1-->4)-beta-D-GlcpNAc-(1-->2)-alpha-D-Manp element that is part of N-linked carbohydrate chains of human lutropin. 920 38

Fecal constituents such as bile acids and increased sialylation of membrane glycoproteins by alpha-2,6-sialyltransferase (HST6N-1) may contribute to colorectal tumorigenesis. We hypothesized that bile acids and phorbol ester [12-O-tetradecanoylphorbol-13-acetate (TPA)] would upregulate HST6N-1 in colonic cells. However, deoxycholate (DOC) (300 mumol/l), a secondary bile acid, and TPA (20 ng/ml) decreased expression of an approximately 100-kDa glycoprotein bearing alpha-2,6-linked sialic acid in a colon cancer cell line (T84) in vitro. HST6N-1 mRNA levels were reduced approximately 80% by treatment (< or = 24 h) with DOC or TPA but not by cholate, a primary bile acid. Treatment (24 h) with DOC or TPA decreased activity of this enzyme to 30% and 13% of control, respectively. These effects of DOC and TPA were transcriptional and were mediated by Ca2+ and protein kinase C, respectively. Thus DOC and TPA both downregulated, and did not upregulate, alpha-2,6-sialyltransferase expression in vitro, but by different transduction pathways. As colorectal tumors grow, their progressive removal from the fecal milieu that normally downregulates this enzyme may favor invasion and metastasis.
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PMID:Downregulation of a human colonic sialyltransferase by a secondary bile acid and a phorbol ester. 953 Jan 63

Sialyl-Lex (sLex) antigen expression recognized by KM93 monoclonal antibody was significantly down-regulated during differentiation induced by 12-O-tetradecanoylphorbol-13-acetate (TPA) in human pre-B lymphocytic leukemia cell line KM3. The sLex determinants were almost exclusively expressed on O-linked oligosaccharide chains of an O-glycosylated 150-kDa glycoprotein (gp150). A low shear force cell adhesion assay showed that TPA treatment significantly inhibited E-selectin-mediated cell adhesion. Transcript and/or enzyme activity levels of alpha1-->3-fucosyltransferase, alpha2-->3-sialyltransferase, beta1-->4-galactosyltransferase, and elongation beta1-->3-N-acetylglucosaminyltransferase did not correlate with sLex expression levels. However, transcript and enzyme activity levels of core 2 GlcNAc-transferase (C2GnT) were significantly down-regulated during TPA treatment. Following transfection and constitutive expression of full-length exogenous C2GnT transcript, C2GnT enzyme activities were maintained at high levels even after TPA treatment and down-regulation of cell surface sLex antigen expression by TPA was completely abolished. Furthermore, in the transfected cells, the KM93 reactivity of gp150 was not reduced by TPA treatment, and the inhibition of cell adhesion by TPA was also blocked. These results suggest that sLex expression is critically regulated by a single glycosyltransferase, C2GnT, during differentiation of KM3 cells.
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PMID:Single glycosyltransferase, core 2 beta1-->6-N-acetylglucosaminyltransferase, regulates cell surface sialyl-Lex expression level in human pre-B lymphocytic leukemia cell line KM3 treated with phorbolester. 975 22


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