Keratan sulfate

About: Keratan sulfate is a research topic. Over the lifetime, 1253 publications have been published within this topic receiving 57984 citations. The topic is also known as: keratan sulfate & KS.

Nitrous acid degradation of glycosaminoglycans.

Abstract: Glycosaminoglycans (GAGs) are made up of disaccharide units that are distinguished from each other by the monosaccharide units of which they are composed and by the degree and position of sulfation. These disaccharide units represent the monomeric units of the GAG; thus, measurement of the disaccharide composition of a GAG represents the first step in the characterization of the polymer. In this unit, cleavage of the glycosidic bonds of the N-sulfated GlcN residues in heparin and heparan sulfate is described, in addition to cleavage of the bonds between the N-acetylated amino sugar residues in heparin, heparan sulfate, chondroitin sulfate, dermatan sulfate, and keratan sulfate, and hyaluronic acid. Using these procedures involving, all GAGs can be converted completely to their constituent disaccharides and reduced with NaB[3H]4) to yield labeled disaccharides that can be assayed qualitatively or quantitatively. The procedure may also be used to analyze metabolically labeled GAGs (with or without the use of NaB[3H]4).

Corneal Sulfated Glycosaminoglycans and Their Effects on Trigeminal Nerve Growth Cone Behavior In Vitro: Roles for ECM in Cornea Innervation

Abstract: PURPOSE Sensory trigeminal nerve growth cones innervate the cornea in a highly coordinated fashion. The purpose of this study was to determine if extracellular matrix glycosaminoglycans (ECM-GAGs), including keratan sulfate (KS), dermatan sulfate (DS), and chondroitin sulfate A (CSA) and C (CSC), polymerized in developing eyefronts, may provide guidance cues to nerves during cornea innervation. METHODS Immunostaining using antineuron-specific-β-tubulin and monoclonal antibodies for KS, DS, and CSA/C was performed on eyefronts from embryonic day (E) 9 to E14 and staining visualized by confocal microscopy. Effects of purified GAGs on trigeminal nerve growth cone behavior were tested using in vitro neuronal explant cultures. RESULTS At E9 to E10, nerves exiting the pericorneal nerve ring grew as tight fascicles, advancing straight toward the corneal stroma. In contrast, upon entering the stroma, nerves bifurcated repeatedly as they extended anteriorly toward the epithelium. KS was localized in the path of trigeminal nerves, whereas DS and CSA/C-rich areas were avoided by growth cones. When E10 trigeminal neurons were cultured on different substrates comprised of purified GAG molecules, their neurite growth cone behavior varied depending on GAG type, concentration, and mode of presentation (immobilized versus soluble). High concentrations of immobilized KS, DS, and CSA/C inhibited neurite growth to varying degrees. Neurites traversing lower, permissive concentrations of immobilized DS and CSA/C displayed increased fasciculation and decreased branching, whereas KS caused decreased fasciculation and increased branching. Enzymatic digestion of sulfated GAGs canceled their effects on trigeminal neurons. CONCLUSIONS Data herein suggest that GAGs may direct the movement of trigeminal nerve growth cones innervating the cornea.

Corneal glycosaminoglycan synthesis in long-term organ culture.

Abstract: types. Physical or enzymatic damage to the cultured corneas resulted in marked changes in the ratio of labeled GAG types secreted. Physical damage to the epithelial or endothelial surfaces and/or mild trypsin treatment of the corneas before culture resulted in a stimulation of galactosaminoglycan secretion and a consequent decrease in the relative abundance of keratan sulfate. The presence of soy trypsin inhibitor prevented these changes. Treatment of the corneas with collagenase resulted in a decrease in all GAG secretion, particularly keratan sulfate. When corneas were removed from chilled, enucleated eyes and rinsed with solutions of soy trypsin inhibitor before incubation, the GAG secreted in culture had a similar ratio of keratan sulfate to galactosaminglycan as GAG labeled in vivo. This ratio was maintained 1 week in culture. These results suggest that secretion of the characteristic connective tissue of the corneal stroma by keratocytes is dependent on interaction between the cells and components of the stromal extracellular matrix. Invest Ophthalmol Vis Sci 24:208-213, 1983 In adult animals, corneal connective tissue is secreted by the stromal keratocytes, flattened mesenchymal cells located between the stromal lamellae. For short periods of time in organ culture, keratocytes continue to secrete characteristic stromal connective tissue components. 1 After 48 hours in organ or cell culture, marked changes take place in the nature of these secretions. A well-characterized aspect of this change is the alteration in corneal glycosaminglycan synthesis. There are two major corneal types of glycosaminoglycan (GAG), keratan sulfate and galactosaminglycan (a chondroitin sulfate-dermatan sulfate hybrid). In vivo, more than half of the total GAG secreted by keratocytes is keratan sulfate, but after 48 hours in organ or cell culture, this level decreases to 10% or less of the total. 23 Keratocytes grown in