Stimulation by concanavalin A of cartilage-matrix proteoglycan synthesis in chondrocyte cultures.
The effect of concanavalin A on proteoglycan synthesis by rabbit costal and articular chondrocytes was examined. Chondrocytes were seeded at low density and grown to confluency in medium supplemented with 10% fetal bovine serum, and then the serum concentration was reduced to 0.3%. At the low serum concentration, chondrocytes adopted a fibroblastic morphology. Addition of concanavalin A to the culture medium induced a morphologic alteration of the fibroblastic cells to spherical chondrocytes and increased by 3- to 4-fold incorporation of [35S]sulfate and [3H]glucosamine into large chondroitin sulfate proteoglycan that was characteristically found in cartilage. The stimulation of incorporation of labeled precursors reflected real increases in proteoglycan synthesis, as chemical analyses showed a 4-fold increase in the accumulation of macromolecules containing hexuronic acid in concanavalin A-maintained cultures. Furthermore, the effect of concanavalin A on [35S]sulfate incorporation into proteoglycans was greater than that of various growth factors or hormones. However, concanavalin A had smaller effects on [35S]sulfate incorporation into small proteoglycans and [3H]glucosamine incorporation into hyaluronic acid and chondroitinase AC-resistant glycosaminoglycans. Since other lectins tested, such as wheat germ agglutinin, lentil lectin, and phytohemagglutinin, had little effect on [35S]sulfate incorporation into proteoglycans, the concanavalin A action on chondrocytes seems specific. Although concanavalin A decreased [3H]thymidine incorporation in chondrocytes, the stimulation of proteoglycan synthesis could be observed in chondrocytes exposed to the inhibitor of DNA synthesis, cytosine arabinoside. These results indicate that concanavalin A is a potent modulator of proteoglycan synthesis by chondrocytes.
Yan
W Q
WQ
Department of Biochemistry, Faculty of Dentistry, Osaka University, Japan.
Nakashima
K
K
Iwamoto
M
M
Kato
Y
Y
D000818:Animals; D002241:Carbohydrates; D002356:Cartilage / Q000166:cytology / Q000187:drug effects / Q000378:metabolism*; D002358:Cartilage, Articular / Q000166:cytology / Q000187:drug effects / Q000378:metabolism*; D002478:Cells, Cultured; D003208:Concanavalin A / Q000494:pharmacology*; D003470:Culture Media; D004261:DNA Replication / Q000187:drug effects; D005944:Glucosamine / Q000378:metabolism; D006025:Glycosaminoglycans / Q000096:biosynthesis; D007700:Kinetics; D037102:Lectins / Q000494:pharmacology; D008213:Lymphocyte Activation; D011509:Proteoglycans / Q000096:biosynthesis*; D011817:Rabbits; D013329:Structure-Activity Relationship; D013431:Sulfates / Q000378:metabolism; D013462:Sulfur Radioisotopes; D014316:Tritium
D002241:Carbohydrates; D003470:Culture Media; D006025:Glycosaminoglycans; D037102:Lectins; D011509:Proteoglycans; D013431:Sulfates; D013462:Sulfur Radioisotopes; D014316:Tritium; D003208:Concanavalin A; D005944:Glucosamine