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Query: EC:3.1.6.4 (chondroitinase)
 2,039 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Recent studies have demonstrated that basic fibroblast growth factor (bFGF) plays a key role in the terminal differentiation of growth plate chondrocytes during endochondral ossification. In this paper we examined the potential role of heparan sulfate in the regulation of the action of basic fibroblast growth factor (bFGF) in the terminal differentiation of rat growth plate chondrocytes. As rat growth plate chondrocytes differentiate in vitro, the percentage of heparitinase-sensitive material decreases. Treatment of growth plate chondrocytes with sodium chlorate, a reversible inhibitor of glycosaminoglycan sulfation, resulted in terminal differentiation of growth plate chondrocytes even in the presence of bFGF at concentrations that normally repress their differentiation. Chlorate treatment in the presence of bFGF resulted in an increase in alkaline phosphatase activity and a decrease in cellular proliferation, both characteristics of the differentiated state. Chlorate treatment also reduced the binding of bFGF to growth plate chondrocytes and this effect could be reversed in a dose-dependent manner by the simultaneous addition of sodium sulfate. The reduced binding was a function of a reduced number of receptors and not a reduced affinity for the receptor. Pretreatment of the growth plate chondrocytes with heparitinase significantly reduced the binding of bFGF to both low- and high-affinity receptors, while pretreatment with chondroitinase ABC had no effect. Finally, addition of exogenous heparin restored bFGF binding to chlorate-treated chondrocytes in a concentration-dependent manner. These results provide evidence that a cell surface heparan sulfate is involved in the binding of bFGF to high-affinity receptors and that a downregulation of this glycosaminoglycan is part of the pathway that leads to terminal differentiation of growth plate chondrocytes.
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PMID:Role of heparan sulfate in the terminal differentiation of growth plate chondrocytes. 784 Jun 21

Proteoglycans have been implicated in the clustering of acetylcholine receptors (AChRs) on cultured myotubes and at the neuromuscular junction. We report that the presence of chondroitin sulfate is associated with the ability of cultured myotubes to form spontaneous clusters of AChRs. Three experimental manipulations of wild type C2 cells in culture were found to affect both glycosaminoglycans (GAGs) and AChR clustering in concert. Chlorate was found to have dose-dependent negative effects both on GAG sulfation and on the frequency of AChR clusters. When extracellular calcium was raised from 1.8 to 6.8 mM in cultures of wild-type C2 myotubes, increases were observed both in the level of cell layer-associated chondroitin sulfate and in the frequency of AChR clusters. Culture of wild-type C2 myotubes in the presence of chondroitinase ABC eliminated cell layer-associated chondroitin sulfate while leaving heparan sulfate intact and simultaneously prevented the formation of AChR clusters. Treatment with either chlorate or chondroitinase inhibited AChR clustering only if begun prior to the spontaneous formation of clusters. We propose that chondroitin sulfate plays an essential role in the initiation of AChR clustering and in the early events of synapse formation on muscle.
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PMID:Acetylcholine receptor clustering in C2 muscle cells requires chondroitin sulfate. 859 8

Proteoglycans (PGs) have been shown to play a key role in the development of many tissues. We have investigated the role of sulfated PGs in early rat lung development by treating cultured tissues with 30 mM sodium chlorate, a global inhibitor of PG sulfation. Chlorate treatment disrupted growth and branching of embryonic day 13 lung explants. Isolated lung epithelium (LgE) migrated toward and invaded lung mesenchyme (LgM), and chlorate irreversibly suppressed this response. Chlorate also inhibited migration of LgE toward beads soaked in FGF10. Chlorate severely decreased branching morphogenesis in tissue recombinants consisting of LgM plus either LgE or tracheal epithelium (TrE) and decreased expression of surfactant protein C gene (SP-C). Chlorate also reduced bone morphogenetic protein-4 expression in cultured tips and recombinants but had no effect on the expression of clara cell 10-kDa protein (CC10), sonic hedgehog (Shh), FGF10, and FGF receptor 2IIIb. Chlorate reduced the growth of LgE in mesenchyme-free culture but did not affect SP-C expression. In contrast, chlorate inhibited both rudiment growth and the induction of SP-C in mesenchyme-free cultured TrE. Treatment of lung tips and tissue recombinants with chondroitinase ABC abolished branching morphogenesis. Chondroitinase also suppressed growth of TrE in mesenchyme-free culture. Chondroitinase treatment, however, had no effect on the induction of SP-C expression in any of these cultures. These results demonstrate the overall importance of sulfated PGs to normal lung development and demonstrate a dynamic role for chondroitin sulfate PGs in embryonic lung growth and morphogenesis.
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PMID:Chondroitin sulfate proteoglycans are required for lung growth and morphogenesis in vitro. 1292 82