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Discussion 8 Hyaluronan, Sulfated Glycosaminoglycans & Glycosaminoglycan Binding Proteins.

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Presentation on theme: "Discussion 8 Hyaluronan, Sulfated Glycosaminoglycans & Glycosaminoglycan Binding Proteins."— Presentation transcript:

1 Discussion 8 Hyaluronan, Sulfated Glycosaminoglycans & Glycosaminoglycan Binding Proteins

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

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5     6S NSNS3S2SNS  IdoA Sulfated Glycosaminoglycans   6S HONO GalNAcGlcA    6S4S 4S6S4S 2S IdoA 

6 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

7 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

8 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

9 Aggrecan Family Chondroitin sulfate

10 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

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

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

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

14 Hyaluronan as a Scaffold Hyaluronic Acid Aggrecan

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16 ABC

17 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

18 Antithrombin-Heparin

19 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

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

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

22  6S NS 6S NS 6S NS2S  6S NS 6S NS2S 

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


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