Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: EC:2.4.99.7 (sialyltransferase)
 1,534 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Human fibroblast cell line WI-38 cultured in vitro was treated with a human recombinant IL-4 at concentrations of 1 to 100 U/ml to examine the alteration of glycosphingolipid (GSL) expression of the cells. Neutral GSL of non-treated WI-38 cells consisted of CMH (GlcCer), CDH, CTH, and Gb4Cer; CMH and CTH were the major components. The acidic GSL were composed of GM3 as the predominant component and other minor gangliosides including GD3. The neutral GSLs did not change in profile during the treatment with IL-4, while the acidic GSLs showed a prominent change, an increase of GD3 content. The increase of GD3 was detectable with IL-4 concentrations over 1 U/ml, and reached a plateau at 10 U/ml, where the amount of GD3 was almost equal to that of GM3. The GD3 increase occurred at 24 h after the IL-4 treatment, and lasted for at least 96 h, as long as IL-4 remained present in the culture media. The GD3 synthase (sialyltransferase) level was found to be increased in an IL-4 dose-dependent manner. IL-4 did not influence the growth or morphological appearance of WI-38 cells. The results demonstrate a novel biological effect of IL-4, modulating GSL in non-hematopoietic cells.
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PMID:Interleukin 4 enhances ganglioside GD3 expression on the human fibroblast cell line WI-38. 760 18

In lesions of malignant melanoma, melanoma cells are exposed to various cytokines produced by inflammatory reactions. As a result, transformation of melanoma cells is expected to occur. We studied alterations in human melanoma cell line ganglioside composition after exposing melanoma cell lines to interferon (IFN)-gamma, interleukin (IL)-2, and IL-4 by biochemical methods. IFN-gamma increases the ratio of a-series gangliosides and the ratio of GM3/GD3. This suggests an alteration of immunoreactivity, a decrease in ganglioside sialyltransferase II activity, and an decrease in the malignant character of these cells. The alteration of the ganglioside profile varied among cytokines and cell lines. The progression of malignant melanoma may be influenced by reciprocal interactions between the melanoma cells and the host immune system.
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PMID:Alteration of human melanoma gangliosides by IFN-gamma, IL-2, and IL-4. 893 35

We have previously shown that costimulation of endothelial cells with IL-1 + IL-4 markedly inhibits VCAM-1-dependent adhesion under flow conditions. We hypothesized that sialic acids on the costimulated cell surfaces may contribute to the inhibition. Northern blot analyses showed that Gal beta 1-4GlcNAc alpha 2, 6-sialyltransferase (ST6N) mRNA was up-regulated in cultured HUVEC by IL-1 or IL-4 alone, but that the expression was enhanced by costimulation, whereas the level of Gal beta 1-4GlcNAc/Gal beta 1-3GalNAc alpha2,3-sialyltransferase (ST3ON) mRNA was unchanged. Removing both alpha 2,6- and alpha 2,3-linked sialic acids from IL-1 + IL-4-costimulated HUVEC by sialidase significantly increased VCAM-1-dependent adhesion, whereas removing alpha 2,3-linked sialic acid alone had no effect; adenovirus-mediated overexpression of ST6N with costimulation almost abolished the adhesion, which was reversible by sialidase. The same treatments of IL-1-stimulated HUVEC had no effect. Lectin blotting showed that VCAM-1 is decorated with alpha 2,6- but not alpha 2,3-linked sialic acids. However, overexpression of alpha 2,6-sialyltransferase did not increase alpha 2,6-linked sialic acid on VCAM-1 but did increase alpha 2,6-linked sialic acids on other proteins that remain to be identified. These results suggest that alpha 2,6-linked sialic acids on a molecule(s) inducible by costimulation with IL-1 + IL-4 but not IL-1 alone down-regulates VCAM-1-dependent adhesion under flow conditions.
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PMID:Endothelial alpha 2,6-linked sialic acid inhibits VCAM-1-dependent adhesion under flow conditions. 1045 33

Nematode infections induce the upregulation of mucin- and glycosylation-related genes in intestinal epithelial cells in vivo. However, the factor(s) that induce these changes in epithelial cells have not been fully elucidated. In the present study, we analysed the effects of the Th2 cytokines IL-4 and IL-13 and the excretory-secretory (ES) product of the nematode Nippostrongylus brasiliensis on the gene expression of the major mucin core peptide MUC2, the sialyltransferase ST3GalIV (Siat4c) and the sulphotransferase HS3ST1 in intestinal epithelium-derived IEC-6 cells by quantitative reverse transcription (RT)-PCR. The administration of IL-4 and IL-13 resulted in a significant upregulation of ST3GalIV and HS3ST1 gene transcription, but had no effect on MUC2, in IEC-6 cells. RT-PCR studies also demonstrated the constitutive expression of IL-13Ralpha1 and IL-4R in IEC-6 cells. On the other hand, the ES product induced upregulation of ST3GalIV, but not HS3ST1 or MUC2, while coadministration of IL-13 and the ES product induced a slight but significant upregulation of MUC2. Co-incubation of live N. brasiliensis adult worms with IEC-6 cells resulted in the upregulation of ST3GalIV and MUC2. These results suggested that HS3ST1 gene expression is strictly regulated by IL-4/IL-13, while ST3GalIV and MUC2 gene expressions are regulated by redundant mechanisms.
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PMID:Direct effects of IL-4/IL-13 and the nematode Nippostrongylus brasiliensis on intestinal epithelial cells in vitro. 2050 Jun 73

Sialic acid-binding, Ig-like lectin (Siglec)-F is highly expressed on mouse eosinophils and plays an important role in regulating levels of eosinophilic lung inflammation. In this study we investigated the mechanism of constitutive and inducible Siglec-F ligand expression by lung airway epithelial cells and inflammatory cells in wild-type (WT) and genetically altered mice (ST3Gal-III heterozygotes, Fuc-TIV/VII double null, STAT6 null). Flow cytometry demonstrated that Siglec-F ligands are constitutively expressed in vitro and in vivo in selected lung cell types (epithelial cells, eosinophils, macrophages, and mast cells, but not CD4, CD8, or B cells) and are induced in response to divergent stimuli, including innate stimuli (TLR ligands, Alternaria), Th2 cytokines (IL-4, IL-13), and adaptive immune stimuli (OVA allergen). Furthermore, studies of deficient mice demonstrated the greater importance of the sialyltransferase ST3Gal-III compared with fucosyltransferases Fuc-TIV/VII in the synthesis of the constitutive and inducible Siglec-F ligands by lung epithelial and nonepithelial cells. In keeping with this, ST3Gal-III heterozygote mice (deficient in expression of Siglec-F ligands) also had significantly enhanced OVA-induced eosinophilic airway inflammation associated with reduced eosinophil apoptosis. Reduced eosinophil apoptosis in the lung of ST3Gal-III-deficient mice is likely mediated by reduced epithelial expression of Siglec-F ligands as WT eosinophils (which highly express Siglec-F) cultured with ST3Gal-III-deficient epithelial cells (which do not express Siglec-F ligand) showed reduced eosinophil apoptosis compared with WT eosinophils cultured with WT epithelial cells. Overall, these studies demonstrate that ST3Gal-III plays an important role in Siglec-F ligand formation and eosinophil apoptosis with resultant effects on eosinophilic inflammation in the lung.
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PMID:Sialyltransferase ST3Gal-III regulates Siglec-F ligand formation and eosinophilic lung inflammation in mice. 2367 75

IgA nephropathy (IgAN), the most common primary glomerulonephritis, is characterized by renal immunodeposits containing IgA1 with galactose-deficient O-glycans (Gd-IgA1). These immunodeposits originate from circulating immune complexes consisting of anti-glycan antibodies bound to Gd-IgA1. As clinical disease onset and activity of IgAN often coincide with mucosal infections and dysregulation of cytokines, we hypothesized that cytokines may affect IgA1 O-glycosylation. We used IgA1-secreting cells derived from the circulation of IgAN patients and healthy controls and assessed whether IgA1 O-glycosylation is altered by cytokines. Of the eight cytokines tested, only IL-6 and, to a lesser degree, IL-4 significantly increased galactose deficiency of IgA1; changes in IgA1 O-glycosylation were robust for the cells from IgAN patients. These cytokines reduced galactosylation of the O-glycan substrate directly via decreased expression of the galactosyltransferase C1GalT1 and, indirectly, via increased expression of the sialyltransferase ST6GalNAc-II, which prevents galactosylation by C1GalT1. These findings were confirmed by siRNA knockdown of the corresponding genes and by in vitro enzyme reactions. In summary, IL-6 and IL-4 accentuated galactose deficiency of IgA1 via coordinated modulation of key glycosyltransferases. These data provide a mechanism explaining increased immune-complex formation and disease exacerbation during mucosal infections in IgAN patients.
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PMID:Cytokines alter IgA1 O-glycosylation by dysregulating C1GalT1 and ST6GalNAc-II enzymes. 2439 80