Structure/function characterization of porcine CD59: expression, chromosomal mapping, complement-inhibition, and costimulatory activity.
BACKGROUND
Complement regulatory proteins have become important targets to potentially modulate inflammatory reactions or transplant rejection. Since pig into human xenotransplantation could potentially overcome the enormous shortage of donor organs and tissues, characterization of porcine complement regulatory proteins is critical.


METHODS
The porcine CD59 cDNA has been isolated from porcine aortic endothelial cells and its structure determined. In addition, a molecular genetic analysis of the gene and its transcriptional properties and a functional analysis have been performed utilizing the transfected cDNA.


RESULTS
The most prominent mRNA species is 1.8 kilobases but cloned reverse transcriptase polymerase chain reaction products suggest that multiple polyadenylation sites are utilized. Gene mapping was performed utilizing a polymorphism identified in the 3' UT, and the gene was localized to within 3 cM of follicle-stimulating hormone, beta polypeptide in the middle of the chromosome 2 linkage map. RNA expression was equivalent in endothelial, kidney, and testis cell lines. Comparisons have been made with CD59 sequences from other species to identify possible important domains of the protein. The cDNA has been utilized to express an epitope-tagged or wild-type protein either transiently on COS-7 cells or stably in Chinese hamster ovary cells. The porcine CD59 protein effectively inhibited the antibody-mediated lytic activity of both porcine and human complement. In contrast to human CD59, porcine CD59 is incapable of providing costimulation to human T cells.


CONCLUSIONS
These data suggest that overexpression of porcine CD59 might be more effective than human CD59 in prolonging xenograft survival with transgenic pig organs because of reduced immunoreactivity.
Maher
S E
SE
Section of Immunobiology, Yale University School of Medicine, New Haven, Connecticut 06520-8011, USA.
Pflugh
D L
DL
Larsen
N J
NJ
Rothschild
M F
MF
Bothwell
A L
AL
D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D018957:CD59 Antigens / Q000235:genetics* / Q000276:immunology* / Q000502:physiology; D016466:CHO Cells; D002874:Chromosome Mapping; D003165:Complement System Proteins / Q000502:physiology; D006224:Cricetinae; D018076:DNA, Complementary / Q000235:genetics; D006801:Humans; D008969:Molecular Sequence Data; D012313:RNA / Q000378:metabolism; D013329:Structure-Activity Relationship; D013552:Swine; D013601:T-Lymphocytes / Q000502:physiology
D018957:CD59 Antigens; D018076:DNA, Complementary; D012313:RNA; D003165:Complement System Proteins