Comparison of the expression of cell surface poly-N-acetyllactosamine-type oligosaccharides in PC12 cells with those in its variant PC12D.
To explore the biological role of carbohydrate chains in the process of nerve cell differentiation, we carried out a characterization of the carbohydrate structure of glycoproteins by comparing conventional PC12 cells with variant cells (PC12D). In vitro metabolic labeling of cells with either [(3)H] glucosamine or [(3)H] threonine, together with tomato lectin staining, revealed that nerve growth factor (NGF) stimulation caused a decrease in the poly-N-acetyllactosamine synthesis of high-molecular-weight glycopeptides from PC12 cells. By comparison, the amount of glycopeptides with poly-N-acetyllactosamine from PC12D cells was already significantly low and it was not changed by NGF stimulation. By assaying the glycosyltransferases that participate in poly-N-acetyllactosamine synthesis, the decrease in the amount of the poly-N-acetyllactosamine in PC12D cells as well as NGF-stimulated PC12 cells could be accounted for by a reduction in the activity of poly-N-acetyllactosamine extension enzyme (GnT-i), because the amount of poly-N-acetyllactosamine in both cells precisely correlated with changes in GnT-i activity, whereas the activities of N-acetylglucosaminyltransferase V (GnT-V) and beta 1-4 galactosyltransferase remained unchanged. These results demonstrate that the decrease in poly-N-acetyllactosamine synthesis in PC12 cells occurred prior to neurite formation, whereas PC12D cells were insensitive to this effect. Next, we showed that GnT-i but not GnT-V catalyzed a rate-limiting reaction in the expression of poly-N-acetyllactosamine chains, especially in pheochromocytoma.
Fukuzumi
M
M
Department of Biotechnology, Faculty of Engineering, Kyoto Sangyo University, Kita-ku, Kyoto 603-8555, Japan.
Maruyama
S
S
Sano
M
M
Fukui
S
S
D000818:Animals; D002240:Carbohydrate Sequence; D002454:Cell Differentiation; D005944:Glucosamine / Q000378:metabolism; D008562:Membrane Glycoproteins / Q000096:biosynthesis*; D008969:Molecular Sequence Data; D017351:N-Acetylglucosaminyltransferases / Q000378:metabolism; D020932:Nerve Growth Factor / Q000494:pharmacology; D016501:Neurites; D009844:Oligosaccharides / Q000096:biosynthesis*; D016716:PC12 Cells / Q000166:cytology / Q000187:drug effects / Q000378:metabolism*; D011134:Polysaccharides / Q000096:biosynthesis*; D051381:Rats
D008562:Membrane Glycoproteins; D009844:Oligosaccharides; D011134:Polysaccharides; C037199:poly-N-acetyllactosamine; D020932:Nerve Growth Factor; D017351:N-Acetylglucosaminyltransferases; C024850:alpha-1,3-mannosyl-glycoprotein beta-1,2-N-acetylglucosaminyltransferase I; D005944:Glucosamine