Showing papers on "Keratan sulfate published in 2023"

Chemistry and Function of Glycosaminoglycans in the Nervous System.

Abstract: Proteoglycans, and especially their GAG components, participate in numerous biologically significant interactions with growth factors, chemokines, morphogens, guidance molecules, survival factors, and other extracellular and cell-surface components. These interactions are often critical to the basic developmental processes of cellular proliferation and differentiation, as well as to both the onset of disease sequelae and prevention of disease progression. In many tissues, proteoglycans and especially their glycosaminoglycan (GAG) components are mediators of these processes. The GAG family is characterized by covalently linked repeating disaccharides forming long unbranched polysaccharide chains. Thus far in higher eukaryotes, the family consists of chondroitin sulfate (CS), heparin/heparan sulfate (HS), dermatan sulfate (DS), keratan sulfate (KS) and hyaluronan (HA). All GAG chains (except HA) are characteristically modified by varying amounts of esterified sulfate. One or more GAG chains are usually found in nature bound to polypeptide backbones in the form of proteoglycans; HA is the exception. In the nervous system, GAG/proteoglycan-mediated interactions participate in proliferation and synaptogenesis, neural plasticity, and regeneration. This review focuses on the structure, chemistry and function of GAGs in nervous system development, disease, function and injury response.

Glycosaminoglycan Analysis: Purification, Structural Profiling, and GAG-Protein Interactions.

Abstract: Glycosaminoglycans (GAGs) are long, linear polysaccharides that are ubiquitously expressed on the cell surface and in the extracellular matrix of all animal cells. These complex carbohydrates are composed of alternating glucosamine and uronic acids that can be heterogeneously N- and O-sulfated. The arrangement and orientation of the sulfated sugar residues specify the location of distinct ligand binding sites on the cell surface, and their capacity to bind ligands impacts cell growth and development, the ability to form tissues and organs, and normal physiology. The heterogeneous nature of GAGs and their inherent structural diversity across different tissues, cell types, and disease states creates challenges to characterizing their structure and function. Here, we describe detailed methods to investigate GAG-protein interactions in vitro and evaluate the structural composition of two classes of sulfated GAGs, heparan sulfate and chondroitin/dermatan sulfate, using liquid chromatography, mass spectrometry, and radiolabeling techniques. Overall, these methods facilitate the evaluation of GAG structure and function to uncover the unique roles these molecules play in cell biology and human disease.

Construction of mouse cochlin mutants with different GAG-binding specificities and their use for immunohistochemistry

Abstract: Glycosaminoglycan (GAG) is a polysaccharide present on the cell surface as an extracellular matrix component, and is composed of repeating disaccharide units consisting of an amino sugar and uronic acid except in the case of the keratan sulfate. Sulfated GAGs, such as heparan sulfate, heparin, and chondroitin sulfate mediate signal transduction of growth factors, and their functions vary with the type and degree of sulfated modification. We have previously identified human and mouse cochlins as proteins that bind to sulfated GAGs. Here, we prepared a recombinant cochlin fused to human IgG-Fc or Protein A at the C-terminus as a detection and purification tag and investigated the ligand specificity of cochlin. We found that cochlin can be used as a specific probe for highly sulfated heparan sulfate and chondroitin sulfate E. We then used mutant analysis to identify the mechanism by which cochlin recognizes GAGs and developed a GAG detection system using cochlin. Interestingly, a mutant lacking the vWA2 domain bound to various types of GAGs. The N-terminal amino acid residues of cochlin contributed to its binding to heparin. Pathological specimens from human myocarditis patients were stained with a cochlin-Fc mutant. The results showed that both tryptase-positive and tryptase-negative mast cells were stained with this mutant. The identification of detailed modification patterns of GAGs is an important method to elucidate the molecular mechanisms of various diseases. The method developed for evaluating the expression of highly sulfated GAGs will help understand the biological and pathological importance of sulfated GAGs in the future.

The versatile roles of lumican in eye diseases: A review.

Abstract: Lumican is a keratan sulfate proteoglycan (KSPG) that belongs to the small leucine-rich proteoglycan family. Research has lifted the veil on the versatile roles of lumican in the pathogenesis of eye diseases. Lumican has pivotal roles in the maintenance of physiological tissue homogenesis and is often upregulated in pathological conditions, e.g., fibrosis, scar tissue formation in injured tissues, persistent inflammatory responses and immune anomaly, etc. Herein, we will review literature regarding the role of lumican in pathogenesis of inherited congenital and acquired eye diseases, e.g., cornea dystrophy, cataract, glaucoma and chorioretinal diseases, etc.

Left-sided valvular heart disease and retinopathy in a 38-year-old woman with attenuated mucopolysaccharidosis: a case report

Abstract: Mucopolysaccharidoses (MPS) are a group of inherited lysosomal storage disorders caused by deficient levels and/or activity of glycosaminoglycan (GAG)-degradative enzymes. MPS are characterized by accumulation of the mucopolysaccharides heparan sulfate, dermatan sulfate, keratan sulfate, or chondroitin sulfate in tissues. We report the case of a 38-year-old woman with a history of joint restriction and retinitis pigmentosa who developed bivalvular heart failure requiring surgery. It was not until pathological examination of surgically excised valvular tissue that a diagnosis of MPS I was made. Her musculoskeletal and ophthalmologic symptoms, when placed in the context of MPS I, painted the diagnostic picture of a genetic syndrome that was overlooked until a diagnosis was made in late middle age.

Bone Growth Induction in Mucopolysaccharidosis IVA Mouse

Abstract: Mucopolysaccharidosis IVA (MPS IVA; Morquio A syndrome) is caused by a deficiency of the N-acetylgalactosamine-6-sulfate-sulfatase (GALNS) enzyme, leading to the accumulation of glycosaminoglycans (GAG), keratan sulfate (KS) and chondroitin-6-sulfate (C6S), mainly in cartilage and bone. This lysosomal storage disorder (LSD) is characterized by severe systemic skeletal dysplasia. To this date, none of the treatment options for the MPS IVA patients correct bone pathology. Enzyme replacement therapy with elosulfase alpha provides a limited impact on bone growth and skeletal lesions in MPS IVA patients. To improve bone pathology, we propose a novel gene therapy with a small peptide as a growth-promoting agent for MPS IVA. A small molecule in this peptide family has been found to exert biological actions over the cardiovascular system. This work shows that an AAV vector expressing a C-type natriuretic (CNP) peptide induces bone growth in the MPS IVA mouse model. Histopathological analysis showed the induction of chondrocyte proliferation. CNP peptide also changed the pattern of GAG levels in bone and liver. These results suggest the potential for CNP peptide to be used as a treatment in MPS IVA patients.

Mice lacking nucleotide sugar transporter SLC35A3 exhibit lethal chondrodysplasia with vertebral anomalies and impaired glycosaminoglycan biosynthesis

Abstract: SLC35A3 is considered an uridine diphosphate N-acetylglucosamine (UDP-GlcNAc) transporter in mammals and regulates the branching of N-glycans. A missense mutation in SLC35A3 causes complex vertebral malformation (CVM) in cattle. However, the biological functions of SLC35A3 have not been fully clarified. To address these issues, we have established Slc35a3–/–mice using CRISPR/Cas9 genome editing system. The generated mutant mice were perinatal lethal and exhibited chondrodysplasia recapitulating CVM-like vertebral anomalies. During embryogenesis, Slc35a3 mRNA was expressed in the presomitic mesoderm of wild-type mice, suggesting that SLC35A3 transports UDP-GlcNAc used for the sugar modification that is essential for somite formation. In the growth plate cartilage of Slc35a3–/–embryos, extracellular space was drastically reduced, and many flat proliferative chondrocytes were reshaped. Proliferation, apoptosis and differentiation were not affected in the chondrocytes of Slc35a3–/–mice, suggesting that the chondrodysplasia phenotypes were mainly caused by the abnormal extracellular matrix quality. Because these histological abnormalities were similar to those observed in several mutant mice accompanying the impaired glycosaminoglycan (GAG) biosynthesis, GAG levels were measured in the spine and limbs of Slc35a3–/–mice using disaccharide composition analysis. Compared with control mice, the amounts of heparan sulfate, keratan sulfate, and chondroitin sulfate/dermatan sulfate, were significantly decreased in Slc35a3–/–mice. These findings suggest that SLC35A3 regulates GAG biosynthesis and the chondrodysplasia phenotypes were partially caused by the decreased GAG synthesis. Hence, Slc35a3−/− mice would be a useful model for investigating the in vivo roles of SLC35A3 and the pathological mechanisms of SLC35A3-associated diseases.

Genotype and Phenotype Characterization of Patients with Mucopolysaccharidosis IV-A in Chile

Abstract: Introduction: Morquio syndrome or mucopolysaccharidosis type IV-A (MPS IV-A) is an autosomal recessive disease caused by biallelic variants in the GALNS gene, encoding the lysosomal enzyme GalN6S, responsible for glycosaminoglycan keratan sulfate and chondroitin-6-sulfate degradation. Studies have shown that the degree of evolutionary and chemical divergence of missense variants in GalN6S when compared to ancestral amino acids is associated with the severity of the syndrome, suggesting a genotype-phenotype correlation. There is little information on Latin American patients with MPS IV-A that replicate these findings. This study aimed to characterize the phenotype and genotype from patients with MPS IV-A, who are under Enzyme Replacement Therapy at the Children’s Neuropsychiatry Service of the Hospital Clínico San Borja Arriarán, Santiago, Chile, and to determine if there is any association between genotype and phenotype with those findings. Methods: Information was collected from medical charts, all patients went through a GalN6S enzymatic activity measurement in leukocytes from peripheral blood, and the GALNS gene was sequenced for all cases. Results: 12 patients with MPS IV-A were recruited, all patients presented multisystem involvement, mostly skeletal, and 75% of cases underwent surgical interventions, and cervical arthrodesis was the most frequent procedure. In regards of the genotype, the two most frequent variants were c.319+2T>C (n = 10, 41.66%) and p.(Arg386Cys) (n = 8, 33.33%), the first one was previously described in 2018 in a patient from Chile [Bochernitsan et al., 2018]. Conclusion: This is the first time that a genotype-phenotype correlation has been studied by analyzing the variants effect on the molecular structure of human GalN6S and the evolutionary conservation degree of affected residues in a cohort of patients in Chile. Albeit our work could not find statistically significant associations, we may infer that the evolutionary conservations of affected amino acids and the effect of variants on enzyme structure may play a main role. Further analyzes should consider a meta-analysis of published cases with genotype data and larger samples and include other variables that could provide more information. Finally, our data strongly suggest that variant c.319+2T>C could have a founder effect in Chilean patients with MPS IV-A.