Reduction of the major swine xenoantigen, the alpha-galactosyl epitope by transfection of the alpha2,3-sialyltransferase gene.
alpha2,3-Sialyltransferase represents a putative enzyme that reduces the Galalpha1-3Gal beta1-4GlcNAc-R (the alpha-galactosyl epitope) by intracellular competition with alpha1,3-galactosyltransferase for a common acceptor substrate. This study demonstrates that the overexpression of the alpha2,3-sialyltransferase gene suppresses the antigenicity of swine endothelial cells to human natural antibodies by 77% relative to control cells and by 30% relative to cells transfected with alpha1,2-fucosyltransferase, and in addition, it reduces the complement-mediated cell lysis by 75% compared with control cells and by 22% compared with cells transfected with alpha1, 2-fucosyltransferase. The mechanism by which the alpha-galactosyl epitope was reduced was also studied. Suppression of alpha1, 3-galactosyltransferase activity by 30-63% was observed in the transfectants with alpha2,3-sialyltransferase, and mRNA expression of the alpha1,3-galactosyltransferase gene was reduced as well. The data suggest that the alpha2,3-sialyltransferase effectively reduced the alpha-galactosyl epitope as well as or better than the alpha1, 2-fucosyltransferase did and that the reduction of the alpha-galactosyl epitope is due not only to substrate competition but also to an overall reduction of endogenous alpha1, 3-galactosyltransferase enzyme activity.
Tanemura
M
M
Department of Biochemistry, Osaka University Medical School, 2-2 Yamadaoka, Suita, Osaka 565-0871, Japan.
Miyagawa
S
S
Koyota
S
S
Koma
M
M
Matsuda
H
H
Tsuji
S
S
Shirakura
R
R
Taniguchi
N
N
D000117:Acetylglucosamine / Q000378:metabolism; D000606:Amino Sugars / Q000378:metabolism; D000818:Animals; D015478:Antigens, Heterophile / Q000378:metabolism*; D002384:Catalysis; D004727:Endothelium / Q000276:immunology / Q000378:metabolism; D000939:Epitopes / Q000378:metabolism*; D005647:Fucosyltransferases / Q000378:metabolism; D005697:Galactosides / Q000276:immunology / Q000378:metabolism*; D006801:Humans; D007770:L-Lactate Dehydrogenase / Q000378:metabolism; D012794:Sialic Acids / Q000378:metabolism; D012799:Sialyltransferases / Q000235:genetics* / Q000378:metabolism; D013552:Swine; D014162:Transfection; D000094663:beta-Galactoside alpha-2,3-Sialyltransferase; D000097631:Galactoside 2-alpha-L-fucosyltransferase
D000117:Acetylglucosamine; D000606:Amino Sugars; D015478:Antigens, Heterophile; D000939:Epitopes; D005647:Fucosyltransferases; D005697:Galactosides; D007770:L-Lactate Dehydrogenase; D012794:Sialic Acids; D012799:Sialyltransferases; D000094663:beta-Galactoside alpha-2,3-Sialyltransferase; D000097631:Galactoside 2-alpha-L-fucosyltransferase; C032233:lactosamine