EFFECT OF CONCANAVALIN A ON MORPHOLOGY AND DNA SYNTHESIS OF RESTING CHONDROCYTE CULTURES
Yan Wei-qun Yang Tong-shu Hou Li-zhong Fujio Suzuki Yukio Kato (Institute of Perclinical Sciences, Norman Bethune University of Medical Sciences, Changchun 130021 The National Lab of Enzyme Engineering. Jilin University, Changchun 130023 Department of Biochemistry, School of Dental, Osaka University, Osaka 565, Japan Department of Biochemisty, School of Dental,Hiroshima University, Hiroshima 734, Japan)
Rabbit chondrocytes were isolated from resting cartilage of ribs of 4-week-old New Zealand rabbits. Chondrocytes were seeded at low density and grown to confluency in medium (DME) with 10% fetal bovine serum, 50 μg/ml ascorbic acid, and antibiotics, at 37℃ under 5% CO2 in air, and then serum concentration was reduced to 0.3%. At the low serum concentration, chondrocytes adopted fibroblastic morphology,Addition of concanavalin A to the culture medium induced a morphologic alteration of the fibroblastic cells to polygonal or spherical chondrocytes that were surrounded by refractile matrix. Wheat germ ag-glutinin and garden pea lectin induced similar cell shape changes without any increase in matrix synthesis. Concanavalin A decreased [3H]thymidine incorporation into DNA in a dose-dependent manner with an ED60 of 0.4-1 μg/ml in the presence of various concentrations of serum ranging from 0.3 to 20%. The concanavalin A inhibition of DNA synthesis was abolished by 10 mmol/L methyl-D-manno-pyranoside. The inhibition of chondrocyte proliferation does not seem to be specific to concanavalin A. Wheat grem agglutinin, lentil lectin, phytohemagglutinin, Ulex europeaus agglutinin, and garden pea lectin also decreased, dose-dependently, [3H]thy-midine incorporation into DNA in chondrocytes. Other lectins at 0.01-20 μg/ml had little effect on [3H] thymidine incorporation. Because the molecular structure of concanavalin A and its mode of actions have been extensively characterized, chondrocytes exposed to this lectin will be useful as a novel model in studying of the control of cellular differentiation.