Chondroitin sulfate N-acetylgalactosaminyltransferase-1 is required for normal cartilage development

Niigata University, Chuo-ku, Japan.
Biochemical Journal (Impact Factor: 4.4). 11/2010; 432(1):47-55. DOI: 10.1042/BJ20100847
Source: PubMed


CS (chondroitin sulfate) is a glycosaminoglycan species that is widely distributed in the extracellular matrix. To understand the physiological roles of enzymes involved in CS synthesis, we produced CSGalNAcT1 (CS N-acetylgalactosaminyltransferase 1)-null mice. CS production was reduced by approximately half in CSGalNAcT1-null mice, and the amount of short-chain CS was also reduced. Moreover, the cartilage of the null mice was significantly smaller than that of wild-type mice. Additionally, type-II collagen fibres in developing cartilage were abnormally aggregated and disarranged in the homozygous mutant mice. These results suggest that CSGalNAcT1 is required for normal CS production in developing cartilage.

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    • "We used 140 male mice aged 9–12 weeks: C57BL/6N (n = 134), BALB/c (n = 2), ICR (n = 2) and N-acetylgalactosaminyltrans- ferase-1 (GalNAcT1)-knockout (n = 2) (Watanabe et al., 2010; Takeuchi et al., 2013). GalNAcT1-knockout mice were used in the experiments for Fig. 1G, BALB/c and ICR mice were used for Fig. 4I and Figs S4C and D, and all other experiments were performed using C57BL/6N mice. "
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    ABSTRACT: While previous studies and brain atlases divide the hypothalamus into many nuclei and areas, uncharacterized regions remain. Here, we report a new region in the mouse anterior hypothalamus (AH), a triangular-shaped perifornical area of the anterior hypothalamus (PeFAH) between the paraventricular hypothalamic nucleus and fornix that abundantly expresses chondroitin sulfate proteoglycans (CSPGs). The PeFAH strongly stained with markers for chondroitin sulfate/CSPGs such as Wisteria floribunda agglutinin and antibodies against aggrecan and chondroitin 6 sulfate. Nissl-stained sections of the PeFAH clearly distinguished it as a region of comparatively low density compared to neighboring regions, the paraventricular nucleus and central division of the anterior hypothalamic area. Immunohistochemical and DNA microarray analyses suggested that PeFAH contains sparsely distributed calretinin-positive neurons and a compact cluster of enkephalinergic neurons. Neuronal tract tracing revealed that both enkephalin- and calretinin-positive neurons project to the lateral septum (LS), while the PeFAH receives input from calbindin-positive LS neurons. These results suggest bidirectional connections between the PeFAH and LS. Considering neuronal subtype and projection, part of PeFAH that includes a cluster of enkephalinergic neurons is comparable with the rat perifornical expression after several types of stimuli and found that PeFAH neuronal activity was increased by psychological but not homeostatic stressors. These findings suggest that the PeFAH is a source of enkephalin peptides in the LS and indicate bidirectional neural connections between these regions may participate in controlling responses to psychological stressors. This article is protected by copyright. All rights reserved. This article is protected by copyright. All rights reserved.
    Full-text · Article · Jul 2015 · European Journal of Neuroscience
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    • "It has been difficult to completely and selectively eliminate CS/DS biosynthesis in vertebrates, most likely due to redundancy between the CS/DS glycosyltransferases . For example, CSGALNACT1- deficient mice, which are viable and fertile but show abnormal cartilage development , still produce 50% of the CS/ DS of wild-type animals (Watanabe et al., 2010). A complete block of CS biosynthesis was achieved in C. elegans resulting in abnormal cytokinesis and morphogenesis (Hwang et al., 2003; Mizuguchi et al., 2003). "
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    ABSTRACT: Background: Chondroitin/dermatan sulfate (CS/DS) proteoglycans present in the extracellular matrix have important structural and regulatory functions. Results: Six human genes have previously been shown to catalyze CS/DS polymerization. Here we show that one of these genes, chpf, is represented by two copies in the zebrafish genome, chpfa and chpfb, while the other five human CS/DS glycosyltransferases csgalnact1, csgalnact2, chpf2, chsy1, and chsy3 all have single zebrafish orthologues. The putative zebrafish CS/DS glycosyltransferases are spatially and temporally expressed. Interestingly, overlapping expression of multiple glycosyltransferases coincides with high CS/DS deposition. Finally, whereas the relative levels of the related polysaccharide HS reach steady-state at around 2 days post fertilization, there is a continued relative increase of the CS amounts per larvae during the first 6 days of development, matching the increased cartilage formation. Conclusions: There are 7 CS/DS glycosyltransferases in zebrafish, which, based on homology, can be divided into the CSGALNACT, CHSY, and CHPF families. The overlap between intense CS/DS production and the expression of multiple CS/DS glycosyltransferases suggests that efficient CS/DS biosynthesis requires a combination of several glycosyltransferases.
    Full-text · Article · Aug 2013 · Developmental Dynamics
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    • "CS is one of the major components of articular cartilage, and Csgalnact1-null mice exhibit some osteoarthritis-like changes in cartilage, such as a decreased level of aggrecan and link protein 1, a rapid catabolism of aggrecan, and abnormally aggregated and disarranged type-II collagen fibers [27], [28]. Contrasting to these mice, histological analysis of mouse knee joints at the age of 1 and 6 months using fast green and safranin O staining showed no articular degradation in any knee joints nor obvious morphologic changes in CSS2−/− mice (Fig. 3). "
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    ABSTRACT: Chondroitin sulfate (CS) is a linear polysaccharide consisting of repeating disaccharide units of N-acetyl-D-galactosamine and D-glucuronic acid residues, modified with sulfated residues at various positions. Based on its structural diversity in chain length and sulfation patterns, CS provides specific biological functions in cell adhesion, morphogenesis, neural network formation, and cell division. To date, six glycosyltransferases are known to be involved in the biosynthesis of chondroitin saccharide chains, and a hetero-oligomer complex of chondroitin sulfate synthase-1 (CSS1)/chondroitin synthase-1 and chondroitin sulfate synthase-2 (CSS2)/chondroitin polymerizing factor is known to have the strongest polymerizing activity. Here, we generated and analyzed CSS2(-/-) mice. Although they were viable and fertile, exhibiting no overt morphological abnormalities or osteoarthritis, their cartilage contained CS chains with a shorter length and at a similar number to wild type. Further analysis using CSS2(-/-) chondrocyte culture systems, together with siRNA of CSS1, revealed the presence of two CS chain species in length, suggesting two steps of CS chain polymerization; i.e., elongation from the linkage region up to Mr ∼10,000, and further extension. There, CSS2 mainly participated in the extension, whereas CSS1 participated in both the extension and the initiation. Our study demonstrates the distinct function of CSS1 and CSS2, providing a clue in the elucidation of the mechanism of CS biosynthesis.
    Full-text · Article · Aug 2012 · PLoS ONE
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