title: In vivo clearance of alpha-1 acid glycoprotein is influenced by the extent of its N-linked glycosylation and by its interaction with the vessel wall.
abstract: Alpha-1 acid glycoprotein (AGP) is a highly glycosylated plasma protein that exerts vasoprotective effects. We hypothesized that AGP's N-linked glycans govern its rate of clearance from the circulation, and followed the disappearance of different forms of radiolabeled human AGP from the plasma of rabbits and mice. Enzymatic deglycosylation of human plasma-derived AGP (pdAGP) by Peptide: N-Glycosidase F yielded a mixture of differentially deglycosylated forms (PNGase-AGP), while the introduction of five Asn to Gln mutations in recombinant Pichia pastoris-derived AGP (rAGP-N(5)Q) eliminated N-linked glycosylation. PNGase-AGP was cleared from the rabbit circulation 9-fold, and rAGP-N(5)Q, 46-fold more rapidly than pdAGP, primarily via a renal route. Pichia pastoris-derived wild-type rAGP differed from pdAGP in expressing mannose-terminated glycans, and, like neuraminidase-treated pdAGP, was more rapidly removed from the rabbit circulation than rAGP-N(5)Q. Systemic hyaluronidase treatment of mice transiently decreased pdAGP clearance. AGP administration to mice reduced vascular binding of hyaluronic acid binding protein in the liver microcirculation and increased its plasma levels. Our results support a critical role of N-linked glycosylation of AGP in regulating its in vivo clearance and an influence of a hyaluronidase-sensitive component of the vessel wall on its transendothelial passage.
authors.affiliation: Department of Pathology and Molecular Medicine, McMaster University, Hamilton, ON L8N 3Z5, Canada.
authors.forename: Teresa R
authors.initials: TR
authors.lastname: McCurdy
authors.forename: Varsha
authors.initials: V
authors.lastname: Bhakta
authors.forename: Louise J
authors.initials: LJ
authors.lastname: Eltringham-Smith
authors.forename: Sharon
authors.initials: S
authors.lastname: Gataiance
authors.forename: Alison E
authors.initials: AE
authors.lastname: Fox-Robichaud
authors.forename: William P
authors.initials: WP
authors.lastname: Sheffield
mesh_terms: D019943:Amino Acid Substitution; D000704:Analysis of Variance; D000818:Animals; D005260:Female; D006031:Glycosylation; D006801:Humans; D018960:Hyaluronan Receptors / Q000378:metabolism; D006821:Hyaluronoglucosaminidase / Q000008:administration & dosage / Q000378:metabolism; D037181:Lectins, C-Type / Q000378:metabolism; D008099:Liver / Q000098:blood supply / Q000378:metabolism; D008297:Male; D000090323:Mannose Receptor; D037241:Mannose-Binding Lectins / Q000378:metabolism; D051379:Mice; D008810:Mice, Inbred C57BL; D009439:Neuraminidase / Q000378:metabolism; D009961:Orosomucoid / Q000008:administration & dosage / Q000737:chemistry / Q000493:pharmacokinetics*; D043524:Peptide-N4-(N-acetyl-beta-glucosaminyl) Asparagine Amidase / Q000378:metabolism; D010843:Pichia / Q000235:genetics; D011817:Rabbits; D011956:Receptors, Cell Surface / Q000378:metabolism; D011994:Recombinant Proteins / Q000008:administration & dosage / Q000737:chemistry / Q000493:pharmacokinetics
chemical_list: D018960:Hyaluronan Receptors; D037181:Lectins, C-Type; D000090323:Mannose Receptor; D037241:Mannose-Binding Lectins; D009961:Orosomucoid; D011956:Receptors, Cell Surface; D011994:Recombinant Proteins; D009439:Neuraminidase; D006821:Hyaluronoglucosaminidase; D043524:Peptide-N4-(N-acetyl-beta-glucosaminyl) Asparagine Amidase