Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: EC:2.4.99.6 (sialyltransferase)
 1,546 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Neurobehavioral testing of herring gull chicks (Larus argentatus) in both laboratory and field studies indicates that lead exposure during critical periods of development causes neurological deficits that may compromise survival in the wild. Accumulating evidence suggests that lead impairs neurodevelopment, in part, by altering the expression of cell adhesion molecules (CAMs) responsible for the proper formation and maintenance of neural structure and synaptic function. We examined the adhesion molecules NCAM, L1, and N-cadherin in gull brains to determine whether these CAMs are altered by lead exposure and might serve as markers of developmental neurotoxicity. One-day-old chicks were collected from nesting colonies and were laboratory housed. On post-hatching day (PHD) 2, chicks were given 100 mg/kg lead acetate or saline (intraperitoneally). Birds were killed on PHD 34, 44, or 55 (blood-lead levels averaged 27.4, 20.8, and 19.5 microg/dl, respectively). Brains were removed and stored at -70 degrees C until analysis. Expression of CAMs was determined in synaptosomal preparations by Western blotting and the activity of NCAM-associated sialyltransferase (ST) was determined in purified whole brain golgi apparatus. Elevation in synaptosomal polysialylated NCAM expression and a significant increase in golgi ST activity was observed in lead-treated animals at PHD 34. Reductions in synaptosomal N-cadherin were observed at PHD 34 and 44, while L1 expression appeared unaffected by lead at any time-point. By 55 days post-hatching, no differences in N-cadherin expression, polysialylated NCAM expression or NCAM-associated ST activity were seen in lead-treated animals as compared with age-matched control animals. Lead-induced disruption of CAM expression during early neurodevelopment may contribute to behavioral deficits observed in herring gulls in both the laboratory and the field, and may serve as a marker for heavy metal exposure during postnatal development.
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PMID:Developmental lead exposure disturbs expression of synaptic neural cell adhesion molecules in herring gull brains. 1081 46

To address the function of carbohydrates in mucins, GalNAcalpha-O-bn has been used in in vivo experiments on several human mucosal cultured cells as a potential competitor of the glycosylation of N-acetylgalactosamine residues. GalNAcalpha-O-bn is metabolized by glycosyltransferases expressed in the cell, and give rise to different internal derivatives starting in particular from the formation of the disaccharide Galalpha1-3GalNAcalpha-O-bn. In this line, GalNAcalpha-O-bn exposure inhibits peripheral glycosylation according a cell-type specific manner. The metabolic alterations are very important in HT-29 cell line, leading to a massive accumulation of GalNAcalpha-O-bn oligosaccharide derivatives and to a strong inhibition of the terminal elongation of O-glycans by alpha2,3 sialyltransferase ST3Gal I. GalNAcalpha-O-bn treatment also induced alterations at the cellular level, exhibiting a large scale in HT-29 cells, i.e. 1) an inhibition of mucin secretion, 2) a blockade in the targeting of some membrane glycoproteins (brush border glycoproteins such as dipeptidylpeptidase IV, carcinoembryonic antigen and the mucin-like glycoprotein MUC1, and the basolateral cell adhesion molecule CD44), 3) an inhibition in the processing of lysosomal enzymes. Morphological abnormalities have been evidenced in GalNAcalpha-O-bn treated cells, in particular the accumulation of numerous intracellular vesicles in HT-29 cells. Taken together, these data suggest that O-glycosylation might be involved in the regulation of the targeting of O-glycosylproteins through carrier vesicles.
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PMID:Inhibition of the glycosylation and alteration in the intracellular trafficking of mucins and other glycoproteins by GalNAcalpha-O-bn in mucosal cell lines: an effect mediated through the intracellular synthesis of complex GalNAcalpha-O-bn oligosaccharides. 1157 61