Discussion 8 Hyaluronan, Sulfated Glycosaminoglycans & Glycosaminoglycan Binding Proteins

 GalNAcGlcA    Chondroitin/ Dermatan Sulfate GlcNAcGlcA   Hyaluronan 6S4S 4S6S4S 2S Glycosaminoglycans (GAG) IdoA      6S NSNS3S2SNS  GlcNAcGlcA IdoA Heparin/ Heparan Sulfate   6S GalNAcGal Keratan Sulfate

    6S NSNS3S2SNS  IdoA Sulfated Glycosaminoglycans   6S HONO GalNAcGlcA    6S4S 4S6S4S 2S IdoA 

CytosolGolgi Ser Galactosyltransferases Glucuronosyltransferase I UDP- Nucleotide sugar transporters n GAG Synthases Sulfated GAG Biosynthesis UDP- UDP-Glc Dehydrogenase UDP- UDP-GlcA Decarboxylase UDP- Xylosyltransferases UDP- S S Sulfotransferases SS

Biosynthesis of a Heparan Sulfate Chain NSNSNSNS 6S6S Gal GlcA Copolymerase Complex EXT1/EXT2 GlcNAc N-deacetylase N-sulfotransferases (NDST) (4 isozymes) 3S GlcNH 2 /S 3-O-sulfotransferases (3OST) (7 isozymes) 2S Uronic acid 2-O-sulfotransferase IdoA Epimerase GlcNAc/S 6-O-sulfotransferases (6OST) (3 + isozymes) 6S GlcNAc EXTL3 Xyl

Proteoglycan Turnover Plasma membrane Endocytosis Step3 exoglycosidase sulfatase Golgi HS oligosaccharide (~10 kDa) HS oligosaccharide (~5 kDa) Proteolytic Shedding Endo-6-sulfatase Heparanase Protease Heparanase

Aggrecan Family Chondroitin sulfate

Interstitial Proteoglycans SLRPs - Small Leucine Rich Proteoglycans GeneKnockouts Decorin (single CS chain) Fragile skin Thin dermis Increased resistance to Borrelia burgdorfei Biglycan (two CS chains) Decrease in bone mass and dentin mineralization Fewer osteoblasts Mild muscular dystrophy Fibromodulin (keratan sulfate) Ectopic tendon ossification Lumican (keratan sulfate) Corneal opacification

Perlecan - Basement Membrane Proteoglycan LDL receptor-like repeats Laminin repeats Ig-like repeats Laminin & EGF motifs 467 KDa

Cell-Binding Domain TM C1 C2 V Glypicans GPI anchored proteins 6 members Syndecans Type I Membrane Proteins 4 members

Hyaluronan n ~ 50,000 

Hyaluronan as a Scaffold Hyaluronic Acid Aggrecan

ABC

O O O OH NSO 3 - OSO 3 - O COO - OH OSO 3 - O O O NSO 3 - ±OSO 3 - O COO - OH OH O NAc OSO 3 - O O Heparan Sulfate Structure is Complex

Antithrombin-Heparin

FGF Heparan sulfate FGF Any Cell Coreceptors Heparan sulfate Depots and Gradients Hh Wnt Basement Membranes and Other ECMs Matrix Proteins Co l Fn Heparan Sulfate Proteoglycans

FGF-Heparin Hexasaccharide Crystal structure shows surface binding 119 KRTGQYKLGSKTGPGQK 135

FGF Mulloy & Linhardt (2001) COSB 11:623 Symmetric structure Heparin interacts with both ligands and receptors Two heparin oligosaccharides present in crystal Heparin

 6S NS 6S NS 6S NS2S  6S NS 6S NS2S 

Heparin versus Heparan Sulfate The difference between heparin and heparan sulfate is quantitative not qualitative     6S NS NS3S 2S NS  2S 6S NS