Protein glycans alteration and a different distribution of some enzymatic activities involved in the glycan processing are found in AZT-treated K562 cells.
In this paper we report that 3'-azido-3'-deoxythymidine (AZT) treatment of human erythroleukemia (K562) cells greatly alters the pattern of protein glycans and significantly modifies beta,(1 --> 4)galactosyltransferase, beta-galactosidase, and alpha,(2 --> 8)sialyltransferase activities. In particular, AZT-treated K562 cells exhibited a decreased incorporation of sialic acid (86% of control) into protein glycans, being the reduced alpha,(2 --> 6) incorporation almost of the same magnitude with respect to that of alpha,(2 --> 3) (93 and 90% of control, respectively). Moreover, the drug exposure of cells induced a decrease of both mannose terminally linked and galactose linked as beta,(1 --> 4) (90 and 92% of control, respectively) and a significant increase of galactose beta,(1 --> 3) (112% of control). In addition, beta,(1 --> 4)galactosyltransferase and beta-galactosidase activities were found enhanced in K562-treated cells (30 and 12%, respectively), while alpha,(2-8 )sialyltransferase activity decreased (75% of control). Sialyltransferase activities of other types i.e. 30, 60, 3 N, 6 N, did not show any appreciable differences irrespective of AZT-treatment. Besides previous studies which report that AZT exposure of K562 cells, indirectly prevents nucleotide-sugar import into the Golgi complex, with consequent inhibition of glycosylation, our observations show for the first time that AZT affects several enzymatic activities involved in specific glycosylation reactions leading, in turn, to protein glycans alteration.
Department of Biomedical Sciences and Technologies, University of L'Aquila, L'Aquila, Italy. gadan@cc.univaq.it
Gabriele
G
D'Andrea
Anna Rita
AR
Lizzi
Fabrizia
F
Brisdelli
Anna Maria
AM
D'Alessandro
Argante
A
Bozzi
Oratore
O
Arduino
D004591:Electrophoresis, Polyacrylamide Gel; D006801:Humans; D020014:K562 Cells; D009237:N-Acetyllactosamine Synthase / Q000378:metabolism*; D011134:Polysaccharides / Q000378:metabolism*; D011522:Protons; D018894:Reverse Transcriptase Inhibitors / Q000494:pharmacology*; D012799:Sialyltransferases / Q000378:metabolism*; D015215:Zidovudine / Q000494:pharmacology*; D001616:beta-Galactosidase / Q000378:metabolism*; D000094802:beta-D-Galactoside alpha 2-6-Sialyltransferase
D011134:Polysaccharides; D011522:Protons; D018894:Reverse Transcriptase Inhibitors; D015215:Zidovudine; D009237:N-Acetyllactosamine Synthase; D012799:Sialyltransferases; D001616:beta-Galactosidase; D000094802:beta-D-Galactoside alpha 2-6-Sialyltransferase