In vivo targeting function of N-linked oligosaccharides with terminating galactose and N-acetylgalactosamine residues.

M.H Chiu,T Tamura,M.S Wadhwa,K.G Rice

doi:10.1016/s0021-9258(17)33992-3

M.H Chiu, T Tamura + Show 2 more

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https://doi.org/10.1016/s0021-9258(17)33992-3

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Abstract

N-Linked biantennary, triantennary, and core fucosylated biantennary oligosaccharides were isolated from animal glycoproteins and derivatized at their reducing end with Boc-tyrosine. The terminal Gal residues were enzymatically removed and replaced with GalNAc. Tyrosinamide-oligosaccharides were radioiodinated and administered intravenously to mice. Pharmacokinetic and biodistribution studies revealed structure-dependent differences in the steady-state volume of distribution, total body clearance rate, and targeting efficiency. Tyrosinamide-oligosaccharides were found to resist metabolism relative to a natural triantennary glycopeptide which was rapidly degraded in vivo. Triantennary oligosaccharides containing terminal Gal or Gal-NAc targeted the liver efficiently whereas biantennary oligosaccharides containing terminal Gal residues and differing only in their core fucosylation avoided recognition by the asialoglycoprotein receptor and were cleared unmetabolized by renal filtration. In contrast, biantennary oligosaccharides containing terminal Gal-NAc residues targeted the liver with much greater efficiency than Gal-terminated triantennary oligosaccharide. Core fucosylation reduced the metabolism rate of tyrosinamide-biantennary in the liver. The results establish the utility of tyrosinamide-oligosaccharides as probes to analyze the ligand specificity of mammalian lectins in vivo and demonstrate that a GalNAc-terminated biantennary is a potent ligand for the asialoglycoprotein receptor.

Highlights

N-Linked biantennary, triantennary, and core fucosy-analyze the specificity of mammalian carbohydrate-protein inlated biantennary oligosaccharides were isolated from teractions [8, 9]
The results es- The present study has examined the in vivo targeting effitablish the utility of tyrosinamide-oligosaccharidesas ciency of triantennary and biantennary oligosaccharides conprobes to analyze the ligand specificity of mammalian taining either 2 or 3 terminal Gal or GalNAc residues
The lectins in vivo anddemonstratethat a GalNAc-termi- results indicate that biantennary oligosaccharides containing nated biantennaryis a potent ligand for the asialogly- terminal GalNAc residue are superior ligands for theASGP-R

Summary

RESULTS

Galactose-terminated N-linked oligosaccharides were prepared from bovine fetuin (Iand III) [16]and porcine fibrinogen [11](17)as t ~ o s i n ~ i d e ~ ligosacchar ipdoessessing a Boc-tyrosine linked to the reducing end GlcNAc through a @-glycosylamide linkage. ~uantitative densitometric analysis of the TLC plates produced a concentration versus time profile that closely mirrored that obtained by direct y counting of blood samples (Fig. 4, B and P ) , In contrast, radioactivity in theblood increased 10 min after administration of glycopeptide IV (Fig, 4C).TLC analysis revealed the presence o f faster migrating iodinated products indicating that the glycopept~dewas rapidly m e t a ~ lized(Fig. Pharmacokinetic parameters were determined from triplicated data setsfor each tyrosinamide-oligosaccharide, averaged to obtain the mean and standard deviation (Table 11). Titative tissuecounting confirmed a liver targeting efficiency of Triantennary oligosaccharide 111 and glycopeptide IV were 5% for I or 11,whereas theradioactivity in thekidney was 3.5%, both targeted to theliver with only minor distribution to other the intestine was 2%, and all other tissues contained backreference tissues (Fig. 5B).Quantitative analysis establisheda ground counts.

Direct tissue counting established a liver targeting efficiency of Proton"

One approach to studying mammalian lectins in vivo is to

Small lntcstlnc Large Intestine