Isolation of bovine corneal keratan sulfate and its growth factor and morphogen binding.
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ABSTRACT:
SUBMITTER: Weyers A
PROVIDER: S-EPMC3651742 | biostudies-literature | 2013 May
REPOSITORIES: biostudies-literature
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Project description:Glycosaminoglycan chains of keratan sulfate proteoglycans appear to be physiologically significant by pairing with tissue lectins. Here, we used NMR spectroscopy and molecular dynamics (MD) simulations to characterize interactions of corneal keratan sulfate (KS), its desulfated form, as well as di-, tetra- (N-acetyllactosamine and lacto-N-tetraose) and octasaccharides with adhesion/growth-regulatory galectins, in particular galectin-3 (Gal-3). The KS contact region involves the lectin canonical binding site, with estimated KD values in the low µM range and stoichiometry of ~ 8 to ~ 20 galectin molecules binding per polysaccharide chain. Compared to Gal-3, the affinity to Gal-7 is relatively low, signaling preferences among galectins. The importance of the sulfate groups was delineated by using desulfated analogs that exhibit relatively reduced affinity. Binding studies with two related di- and tetrasaccharides revealed a similar decrease that underscores affinity enhancement by repetitive arrangement of disaccharide units. MD-based binding energies of KS oligosaccharide-loaded galectins support experimental data on Gal-3 and -7, and extend the scope of KS binding to Gal-1 and -9N. Overall, our results provide strong incentive to further probe the relevance of molecular recognition of KS by galectins in terms of physiological processes in situ, e.g. maintaining integrity of mucosal barriers, intermolecular (lattice-like) gluing within the extracellular meshwork or synaptogenesis.
| S-EPMC7515912 | biostudies-literature
Project description:The keratan sulphate proteoglycans that can be prepared from bovine corneal stroma [Axelsson & Heinegård (1975) Biochem. J. 145, 491-500] were characterized by gel chromatography, gel electrophoresis and analytical ultracentrifugation in associative (0.6 M-NaCl) and dissociative (6M-guanidinum chloride) solvents. The proteoglycans aggreagated at low salt concentrations and pH. The weight-average molecular weight of the monomer proteoglycans was established. Keratan sulphate peptides and oligosaccharide peptides were isolated after proteolysis. Their composition indicated that both are linked to protein via asparagine residues. A tentative model for corneal keratan sulphate proteoglycans is suggested.
| S-EPMC1183825 | biostudies-other
Project description:Keratan sulfate (KS) was isolated from chicken egg white in amounts corresponding to ?0.06 wt% (dry weight). This KS had a weight-average molecular weight of ?36-41 kDa with a polydispersity of ?1.3. The primary repeating unit present in chicken egg white KS was ?4) ?-N-acetyl-6-O-sulfo-d-glucosamine (1 ? 3) ?-d-galactose (1? with some 6-O-sulfo galactose residues present. This KS was somewhat resistant to depolymerization using keratanase 1 but could be depolymerized efficiently through the use of reactive oxygen species generated using copper (II) and hydrogen peroxide. Of particular interest was the presence of substantial amounts of 2,8- and 2,9-linked N-acetylneuraminic acid residues in the form of oligosialic acid terminating the non-reducing ends of the KS chains. Most of the KS appears to be N-linked to a protein core as evidenced by its sensitivity to PNGase F.
| S-EPMC4976520 | biostudies-literature
Project description:PurposeCorneal stroma extracellular matrix (ECM) glycosaminoglycans (GAGs) include keratan sulfate (KS), chondroitin sulfate A (CSA), and hyaluronic acid (HA). Embryonic corneal keratocytes and sensory nerve fibers grow and differentiate according to chemical cues they receive from the ECM. This study asked which of the proteins that may regulate keratocytes or corneal nerve growth cone immigration interact with corneal GAGs.MethodsBiotinylated KS (bKS), CSA (bCSA), and HA (bHA) were prepared and used in microarray protocols to assess their interactions with 8268 proteins and a custom microarray of 85 extracellular epitopes of nerve growth-related proteins. Surface plasmon resonance (SPR) was performed with bKS and SLIT2, and their ka, kd, and KD were determined.ResultsHighly sulfated KS interacted with 217 microarray proteins, including 75 kinases, several membrane or secreted proteins, many cytoskeletal proteins, and many nerve function proteins. CSA interacted with 24 proteins, including 10 kinases and 2 cell surface proteins. HA interacted with 6 proteins, including several ECM-related structural proteins. Of 85 ECM nerve-related epitopes, KS bound 40 proteins, including SLIT, 2 ROBOs, 9 EPHs, 8 Ephrins (EFNs), 8 semaphorins (SEMAs), and 2 nerve growth factor receptors. CSA bound nine proteins, including ROBO2, 2 EPHs, 1 EFN, two SEMAs, and netrin 4. HA bound no ECM nerve-related epitopes. SPR confirmed that KS binds SLIT2 strongly. The KS core protein mimecan/osteoglycin bound 15 proteins.ConclusionsCorneal stromal GAGs bind, and thus could alter the availability or conformation of, many proteins that may influence keratocyte and nerve growth cone behavior in the cornea.
| S-EPMC2941170 | biostudies-literature
Project description:Mucopolysaccharidosis IVA (MPS IVA) is caused by deficiency of N-acetylgalactosamine-6-sulfate sulfatase (GALNS), leading to systemic skeletal dysplasia because of excessive storage of keratan sulfate (KS) in chondrocytes. In an effort to determine a precise prognosis and personalized treatment, we aim to characterize clinical, biochemical, and molecular findings in MPS IVA patients, and to seek correlations between genotype, phenotype, and blood and urine KS levels. Mutation screening of GALNS gene was performed in 55 MPS IVA patients (severe: 36, attenuated: 13, undefined: 6) by genomic PCR followed by direct sequence analysis. Plasma and urine KS levels were measured by ELISA method. Genotype/phenotype/KS correlations were assessed when data were available. Fifty-three different mutations including 19 novel ones (41 missense, 2 nonsense, 4 small deletions, 1 insertion, and 5 splice-site) were identified in 55 patients and accounted for 93.6% of the analyzed mutant alleles. Thirty-nine mutations were associated with a severe phenotype and ten mutations with an attenuated one. Blood and urine KS concentrations in MPS IVA patients were age-dependent and markedly higher than those in age-matched normal controls. Plasma and urine KS levels in MPS IVA patients with the severe phenotype were higher than in those with an attenuated form. This study provides evidence for extensive allelic heterogeneity of MPS IVA. Accumulation of mutations as well as clinical descriptions and KS levels allows us to predict clinical severity more precisely and should be used for evaluation of responses to potential treatment options.
| S-EPMC3779837 | biostudies-literature
Project description:Keratan sulfate (KS) is a sulfated linear polymer of N-acetyllactosamine. Proteoglycans carrying keratan sulfate epitopes were majorly observed in cornea, cartilage and brain; and mainly involved in embryonic development, cornea transparency, and wound healing process. Recently, expression of KS in cancer has been shown to be highly associated with advanced tumor grade and poor prognosis. Therefore, we aimed to identify the expression of KS epitope in human pancreatic cancer primary and metastatic tumor lesions. Immunohistochemical analysis of KS expression was performed on primary pancreatic tumors and metastatic tissues. We observed an increased expression of KS epitope on primary tumor tissues compared to uninvolved normal and tumor stroma; and is associated with worse overall survival. Moreover, lung metastatic tumors show a higher-level expression of KS compared to primary tumors. Interestingly, KS biosynthesis specific glycosyltransferases expression was differentially regulated in metastatic pancreatic tumors. Taken together, these results indicate that aberrant expression of KS is predictive of pancreatic cancer progression and metastasis and may serve as a novel prognostic biomarker for pancreatic cancer.
| S-EPMC6609602 | biostudies-literature
Project description:PurposePrevious studies from this laboratory revealed that vitreous insulin-like growth factor (IGF) biological activity increases in proliferative diabetic retinopathy and that this activity is normally attenuated by IGFBPs. The goal of this study was to identify and characterize the species involved.MethodsHuman and porcine vitreous, plasma, recombinant IGFBP-2, and IGFBP-3 were separated by gel electrophoresis. Functional IGFBPs were detected in Western ligand blots with biotinylated IGF-II. IGFBPs were identified using IGFBP-specific antibodies.ResultsWestern ligand blots of normal vitreous and plasma detected two major proteins at ∼35 kDa and ∼29 kDa. Western blot analysis of human and porcine vitreous and plasma confirmed the identity of the ∼35-kDa band as IGFBP-2 and the ∼29-kDa band as a fragment of IGFBP-3. Western blot and Western ligand blot analyses of vitreous and plasma proteins separated by two-dimensional gel electrophoresis revealed that the IGFBP-3 fragments in vitreous and plasma have virtually identical profiles. Lyase digestion revealed that the ∼29-kDa IGFBP-3 fragment is a glycoprotein with a peptide core of ∼25 kDa. N-terminal sequence data obtained from vitreous IGFBP-3 revealed that the protein is proteolytically truncated at the C terminus. CONCLUSIONS. Normal human and porcine vitreous contain two major IGFBPs, IGFBP-2 and an ∼29-kDa fragment of IGFBP-3. Both IGFBPs retain biological activity, and IGFBP-3 has one or more glycosylation sites with a protein core of ∼25 kDa. Systematic comparisons indicate that the vitreous IGFBP-3 is similar to and perhaps identical with a previously described IGFBP-3 fragment in plasma with reduced growth factor affinities.
| S-EPMC3053280 | biostudies-literature
Project description:Lumican is an extracellular matrix glycoprotein widely distributed in mammalian connective tissues. Corneal lumican modified with keratan sulfate constitutes one of the major proteoglycans of the stroma. Lumican-null mice exhibit altered collagen fibril organization and loss of corneal transparency. A closely related protein, keratocan, carries the remaining keratan sulfate of the cornea, but keratocan-null mice exhibit a less severe corneal phenotype. In the current study, we examined the effect of lumican overexpression in corneas of wild type mice. These mice showed no alteration in collagen organization or transparency but had increased keratocan expression at both protein and mRNA levels. Corneas of lumican-null mice showed decreased keratocan. This coupling of keratocan expression with lumican also was observed after intrastromal injection of a lumican expression minigene into the corneal stroma of Lum-/- mice. Small interfering RNA knockdown of lumican in vitro reduced keratocan expression, whereas co-injection of a lumican-expressing minigene with a beta-galactosidase reporter driven by the keratocan promoter demonstrated an increase of keratocan transcriptional activity in response to lumican expression in Lum-/- corneas in vivo. These observations demonstrate that lumican has a novel regulatory role in keratocan expression at the transcriptional level. Such results help provide an explanation for the differences in severity of corneal manifestation found in Lum-/- and Kera-/- mice. The results also suggest a critical level of small proteoglycans to be essential for collagen organization but that overabundance is not detrimental to extracellular matrix morphogenesis.
| S-EPMC2874675 | biostudies-literature
Project description:Human siglecs are a family of 14 sialic acid-binding proteins, most of which are expressed on subsets of immune cells where they regulate immune responses. Siglec-8 is expressed selectively on human allergic inflammatory cells-primarily eosinophils and mast cells-where engagement causes eosinophil apoptosis and inhibits mast cell mediator release. Evidence supports a model in which human eosinophils and mast cells bind to Siglec-8 sialoglycan ligands on inflammatory target tissues to resolve allergic inflammation and limit tissue damage. To identify Siglec-8-binding sialoglycans from human airways, proteins extracted from postmortem human trachea were resolved by size-exclusion chromatography and composite agarose-acrylamide gel electrophoresis, blotted and probed by Siglec-8-Fc blot overlay. Three size classes of Siglec-8 ligands were identified: 250 kDa, 600 kDa and 1 MDa, each of which was purified by affinity chromatography using a recombinant pentameric form of Siglec-8. Proteomic mass spectrometry identified all size classes as the proteoglycan aggrecan, a finding validated by immunoblotting. Glycan array studies demonstrated Siglec-8 binding to synthetic glycans with a terminal Neu5Acα2-3(6-sulfo)-Gal determinant, a quantitatively minor terminus on keratan sulfate (KS) chains of aggrecan. Treating human tracheal extracts with sialidase or keratanase eliminated Siglec-8 binding, indicating sialylated KS chains as Siglec-8-binding determinants. Treating human tracheal histological sections with keratanase also completely eliminated the binding of Siglec-8-Fc. Finally, Siglec-8 ligand purified from human trachea extracts induced increased apoptosis of freshly isolated human eosinophils in vitro. We conclude that sialylated KS proteoglycans are endogenous human airway ligands that bind Siglec-8 and may regulate allergic inflammation.
| S-EPMC6142871 | biostudies-literature
Project description:Keratan sulfate (KS) is commonly elevated in urine samples from patients with mucopolysaccharidosis type IVA (MPS IVA) and is considered pathognomonic for the condition. Recently, a new method has been described by Martell et al. to detect and measure urinary KS utilizing LC-MS/MS. As a part of the validation of this method in our laboratory, we studied the sensitivity and specificity of elevated urine KS levels using 25 samples from 15 MPS IVA patients, and 138 samples from 102 patients with other lysosomal storage disorders, including MPS I (n?=?9), MPS II (n?=?13), MPS III (n?=?23), MPS VI (n?=?7), beta-galactosidase deficiency (n?=?7), mucolipidosis (ML) type II, II/III and III (n?=?51), alpha-mannosidosis (n?=?11), fucosidosis (n?=?4), sialidosis (n?=?5), Pompe disease (n?=?3), aspartylglucosaminuria (n?=?4), and galactosialidosis (n?=?1). As expected, urine KS values were significantly higher (fivefold average increase) than age-matched controls in all MPS IVA patients. Urine KS levels were also significantly elevated (threefold to fourfold increase) in patients with GM-1 gangliosidosis, MPS IVB, ML II and ML II/III, and fucosidosis. Urine KS was also elevated to a smaller degree (1.1-fold to 1.7-fold average increase) in patients with MPS I, MPS II, and ML III. These findings suggest that while the UPLC-MS/MS urine KS method is 100% sensitive for the detection of patients with MPS IVA, elevated urine KS is not specific for this condition. Therefore, caution is advised when interpreting urinary keratan sulfate results.
| S-EPMC5509552 | biostudies-literature