GLUCOCORTICOID INDUCTION OF THE ALPHA-2,6 SIALYLTRANSFERASE ENZYME INA MOUSE NEURAL CELL-LINE

Combined sialyltransferase (ST) activities were induced in the HN9 hip pocampal cell line following treatment with the synthetic glucocortico id dexamethasone (dex) for 24 hr, Induction occurred in a dose-depende nt manner, with the maximum induction of a 2-fold increase over contro l enzyme levels occurring at a concentration of 10(-8) M dex. A minimu m of 6 hr pretreatment with drug was required before significant induc tion could be detected and elevated enzyme levels persisted for up to 48 hr post-treatment. The induced form of the enzyme showed an increas e in reaction maximum velocity (V-max) while showing no change in affi nity (K-m) for the acceptor substrate asialofetuin. The alpha 2,6 ST e nzyme was demonstrated to be the primary enzyme induced and there was no change in expression of the alpha 2,3 ST enzyme, Lectin blot analys is demonstrated an increase in the levels of the alpha 2,6-linked cell ular sialoglycoproteins and a parallel decrease in the alpha 2,3 sialo glycoprotein levels. (C) 1998 Wiley-Liss, Inc.