T. Ariga et al., ACTIVATION OF UDP-GALACTOSE GLOBOTRIAOSYLCERAMIDE ALPHA-1-3-GALACTOSYLTRANSFERASE DURING PC12D CELL-DIFFERENTIATION INDUCED BY GALACTOSYLCERAMIDE, Biochemistry, 32(31), 1993, pp. 7904-7908
We measured the activities of UDP-galactose:globotriaosylceramide alph
a1-3-galactosyltransferase (alpha-GalTase) and protein kinase C (PKC)
in PC12D pheochromocytoma (PC12D) cells which were induced to differen
tiation by nerve growth factor (NGF), forskolin (FRK), staurosporine (
STP), retinoic acid (RA), 2-chloroadenosine (ClAd), and/or galactosylc
eramide (GalCer). NGF, STP, FRK, and RA were found to be stimulators f
or the PKC activity, whereas ClAd appeared to be an inhibitor of the e
nzyme. At the concentration of 25 muM, GalCer having normal fatty acid
s was found to be a stimulator, whereas GalCer having hydroxy fatty ac
ids was ineffective in modulating the PKC activity. Interestingly, all
stimulators of PKC activities, including GalCer having normal fatty a
cids, appeared to be activators for the alpha-GalTase activity. On the
other hand, GalCer having alpha-hydroxy fatty acids had no effect and
ClAd was found to be a potent inhibitor for the alpha-GalTase activit
y. These data suggest that alpha-GalTase activity during PC12D cell di
fferentiation may be regulated by a PKC-dependent process.