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Title: The molecular basis for galalpha(1,3)gal expression in animals with a deletion of the alpha1,3galactosyltransferase gene.
Austin Authors: Milland, Julie;Christiansen, Dale;Lazarus, Brooke D;Taylor, Simon G;Xing, Pei Xiang;Sandrin, Mauro S 
Affiliation: The Austin Research Institute, Austin Health, Heidelberg, Victoria, Australia
Issue Date: 15-Feb-2006
Publication information: Journal of Immunology (baltimore, Md. : 1950); 176(4): 2448-54
Abstract: The production of homozygous pigs with a disruption in the GGTA1 gene, which encodes alpha1,3galactosyltransferase (alpha1,3GT), represented a critical step toward the clinical reality of xenotransplantation. Unexpectedly, the predicted complete elimination of the immunogenic Galalpha(1,3)Gal carbohydrate epitope was not observed as Galalpha(1,3)Gal staining was still present in tissues from GGTA1(-/-) animals. This shows that, contrary to previous dogma, alpha1,3GT is not the only enzyme able to synthesize Galalpha(1,3)Gal. As iGb3 synthase (iGb3S) is a candidate glycosyltransferase, we cloned iGb3S cDNA from GGTA1(-/-) mouse thymus and confirmed mRNA expression in both mouse and pig tissues. The mouse iGb3S gene exhibits alternative splicing of exons that results in a markedly different cytoplasmic tail compared with the rat gene. Transfection of iGb3S cDNA resulted in high levels of cell surface Galalpha(1,3)Gal synthesized via the isoglobo series pathway, thus demonstrating that mouse iGb3S is an additional enzyme capable of synthesizing the xenoreactive Galalpha(1,3)Gal epitope. Galalpha(1,3)Gal synthesized by iGb3S, in contrast to alpha1,3GT, was resistant to down-regulation by competition with alpha1,2fucosyltransferase. Moreover, Galalpha(1,3)Gal synthesized by iGb3S was immunogenic and elicited Abs in GGTA1 (-/-) mice. Galalpha(1,3)Gal synthesized by iGb3S may affect survival of pig transplants in humans, and deletion of this gene, or modification of its product, warrants consideration.
Gov't Doc #: 16456004
Type: Journal Article
Subjects: Amino Acid Sequence
Base Sequence
Cells, Cultured
Cloning, Molecular
DNA, Complementary.genetics
Gene Deletion
Molecular Sequence Data
RNA, Messenger.genetics
Appears in Collections:Journal articles

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