Ganglioside biosynthesis in rat liver: effect of UDP-amino sugars on individual transfer reactions.
Several glycosyltransferases participating in ganglioside biosynthesis were measured in Golgi-rich fractions from rat liver. Addition of those UDP-amino sugars to the enzyme assays which accumulate in liver after treatment of rats with D-galactosamine inhibited the transferases to different degrees. The simultaneous presence of UDP-GalN, UDP-GalNAc, UDP-GlcN, and UDP-GlcNAc in concentrations resembling their overall content in livers 6 h after D-galactosamine administration led to an inhibition of the glycolipid galactosyltransferases, GL2 and GM1 synthases of 44 and 64%, respectively. GM2 synthase was moderately inhibited whereas the sialyltransferases (GM3, GD3, and GD1a synthases) were almost unimpaired. Induction of liver cell damage by D-galactosamine did not cause any change of glycosyltransferase activities as determined in rat liver homogenates and Golgi-rich fractions. These results indicate a possible role for UDP-amino sugars in the depression of ganglioside biosynthesis observed in vivo after GalN administration.
Schüz-Henninger
R
R
Biochemisches Institut, Albert-Ludwigs-Universität, Freiburg i.Br., Federal Republic of Germany.
Prinz
C
C
Decker
K
K
D000818:Animals; D004305:Dose-Response Relationship, Drug; D005260:Female; D005688:Galactosamine / Q000494:pharmacology; D005700:Galactosyltransferases / Q000037:antagonists & inhibitors; D051147:Ganglioside Galactosyltransferase; D005732:Gangliosides / Q000096:biosynthesis*; D005964:Glucosyltransferases / Q000378:metabolism*; D006028:Glycosphingolipids / Q000096:biosynthesis*; D008099:Liver / Q000187:drug effects / Q000201:enzymology*; D051381:Rats; D011919:Rats, Inbred Strains; D014531:Uridine Diphosphate Galactose / Q000494:pharmacology; D014532:Uridine Diphosphate Glucose / Q000494:pharmacology; D014536:Uridine Diphosphate N-Acetylgalactosamine / Q000494:pharmacology; D014537:Uridine Diphosphate N-Acetylglucosamine / Q000494:pharmacology; D014539:Uridine Diphosphate Sugars / Q000494:pharmacology*
D005732:Gangliosides; D006028:Glycosphingolipids; D014539:Uridine Diphosphate Sugars; D014531:Uridine Diphosphate Galactose; D014537:Uridine Diphosphate N-Acetylglucosamine; D014536:Uridine Diphosphate N-Acetylgalactosamine; D005688:Galactosamine; D005700:Galactosyltransferases; D005964:Glucosyltransferases; D051147:Ganglioside Galactosyltransferase; D014532:Uridine Diphosphate Glucose