An impressive array of proteins with covalently linked carbohydrate is produced by eukaryotic cells as components of secretions, membranes and extracellular matrices (ECM) and their structurally diverse saccharide units have been implicated in a number of recognition phenomena which regulate the interaction of cells with other cells, matrix constituents and circulating molecules. Our objective is to continue and expand our research which is predicated on the belief that an understanding of the biological function and alteration in disease of the carbohydrate-containing proteins depends on a structural definition of their saccharide chains and peptide core. Our broadly based investigations will focus on the structure and functional properties of several groups of glycoconjugates (glycoproteins and proteoglycans) including those from basement membranes and related ECM, mitochondria and thyroid cell surfaces; proteins with sulfated Asn-linked oligosaccharides will also be studied and we will continue to explore the macromolecular derangements of the glomerular ECM responsible for the renal filtration defect of diabetes. More specifically, our investigations will include an assessment of the biological role of heparan sulfate (HS) chains of glomerular basement membrane (GBM) proteoglycan (PC), with their novel 3- 0-sulfated ClcN-containing sequences recently described in this laboratory, in regard to antithrombin binding and antiproliferative activity; characterization of the saccharide sequences and of the core proteins of the HSPG's produced by glomerular cells (mesangial, epithelial and endothelial); polarity studies with the latter two cells to determine why their ECM's have PC's with only HS chains and not chondroitin (CS) and dermatan (DS) sulfate; analyses of diabetic glomerular ECK's for CS and DS as an index of mesangial expansion; characterization of Asn-linked oligosaccharides of type VI collagen which in the glomerulus is mesangially located. Studies on the I-antigenic major thyroid surface glycoprotein (CP-3) in regard to its lipid-glycan anchor cell surface distribution will be continued; the branch and site locations of sulfate capping groups on Asn-linked carbohydrate units of thyroglobulins will be investigated as will be the structure of the sulfated N-linked oligosaccharides of prolactins. A recently initiated study of mitochondrial glycoproteins will be pursued to permit the definition of these molecules in various compartments of this organelle as well as determination of the structure of their carbohydrate units.

National Institute of Health (NIH)
National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK)
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Physiological Chemistry Study Section (PC)
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Joslin Diabetes Center
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Spiro, Robert G (2002) Protein glycosylation: nature, distribution, enzymatic formation, and disease implications of glycopeptide bonds. Glycobiology 12:43R-56R
Edge, A S; Spiro, R G (2000) A specific structural alteration in the heparan sulphate of human glomerular basement membrane in diabetes. Diabetologia 43:1056-9
Spiro, R G; Bhoyroo, V D (1998) Characterization of a spleen sulphotransferase responsible for the 6-O-sulphation of the galactose residue in sialyl-N-acetyl-lactosamine sequences. Biochem J 331 ( Pt 1):265-71
Chandra, N C; Spiro, M J; Spiro, R G (1998) Identification of a glycoprotein from rat liver mitochondrial inner membrane and demonstration of its origin in the endoplasmic reticulum. J Biol Chem 273:19715-21
Karaivanova, V K; Spiro, R G (1998) Sulphation of N-linked oligosaccharides of vesicular stomatitis and influenza virus envelope glycoproteins: host cell specificity, subcellular localization and identification of substituted saccharides. Biochem J 329 ( Pt 3):511-8
Karaivanova, V K; Luan, P; Spiro, R G (1998) Processing of viral envelope glycoprotein by the endomannosidase pathway: evaluation of host cell specificity. Glycobiology 8:725-30
Edge, A S; Spiro, R G (1997) Structure of the O-linked oligosaccharides from a major thyroid cell surface glycoprotein. Arch Biochem Biophys 343:73-80
Spiro, R G; Zhu, Q; Bhoyroo, V et al. (1996) Definition of the lectin-like properties of the molecular chaperone, calreticulin, and demonstration of its copurification with endomannosidase from rat liver Golgi. J Biol Chem 271:11588-94
Shen, G Q; Kresbach, G; Spiro, M J et al. (1995) Evaluation of the cell specificity and sulfate dependence of glomerular extracellular matrix proteoglycan synthesis. Arch Biochem Biophys 321:83-93
Spiro, M J; Spiro, R G (1992) Monosaccharide determination of glycoconjugates by reverse-phase high-performance liquid chromatography of their phenylthiocarbamyl derivatives. Anal Biochem 204:152-7

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