title: Glycoprotein biosynthesis in porcine aortic endothelial cells and changes in the apoptotic cell population.
abstract: Porcine aortic endothelial cells (PAECs) produce glycoproteins with important biological functions, such as the control of cell adhesion, blood clotting, blood pressure, the immune system, and apoptosis. Cell surface glycoproteins play important roles in these biological activities. To understand the control of cell surface glycosylation, we elucidated biosynthetic pathways leading to N- and O-glycans in PAECs. Based on the enzyme activities, PAECs should be rich in complex biantennary N-glycans. In addition, the enzymes synthesizing complex O-glycans with core 1 and 2 structures are present in PAECs. The first enzyme of the O-glycosylation pathway, polypeptide GalNAc-transferase, was particularly active. Its specificity toward synthetic peptide substrates was found to be similar to that of purified bovine colostrum enzyme T1. A significant fraction of PAECs treated with tumour necrosis factor alpha or human serum detached from the culture plate, and most of these cells were apoptotic. The apoptotic cell population exhibited decreased core 2 beta 6-GlcNAc-transferase activity. In contrast, the activities of core 1 beta 3-Gal-transferase, which synthesizes O-glycan core 1, and of alpha 3-sialyltransferase (O), which sialylates core 1, were increased in apoptotic PAECs. Thus, apoptotic PAECs are predicted to have fewer complex O-glycans and a higher proportion of short, sialylated core 1 chains.
authors.affiliation: Department of Medicine, Division of Rheumatology, Queen's University, Kingston, K7L 3N6, Ontario, Canada.
authors.forename: Inka
authors.initials: I
authors.lastname: Brockhausen
authors.forename: Michael
authors.initials: M
authors.lastname: Lehotay
authors.forename: Ji-Mao
authors.initials: JM
authors.lastname: Yang
authors.forename: Wensheng
authors.initials: W
authors.lastname: Qin
authors.forename: David
authors.initials: D
authors.lastname: Young
authors.forename: Jamie
authors.initials: J
authors.lastname: Lucien
authors.forename: John
authors.initials: J
authors.lastname: Coles
authors.forename: Hans
authors.initials: H
authors.lastname: Paulsen
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D001011:Aorta / Q000166:cytology / Q000378:metabolism*; D017209:Apoptosis; D002478:Cells, Cultured; D004730:Endothelium, Vascular / Q000166:cytology / Q000378:metabolism*; D006023:Glycoproteins / Q000096:biosynthesis*; D008969:Molecular Sequence Data; D011134:Polysaccharides / Q000096:biosynthesis; D013552:Swine
chemical_list: D006023:Glycoproteins; D011134:Polysaccharides