Elevated Extracellular Calcium Concentrations Induce Type X Collagen Synthesis in Chondrocyte Cultures

• Published in: The Journal of cell biology Vol. 115; no. 4; pp. 1171 - 1178
• Main Authors: Bonen, Denise K., Schmid, Thomas M.
• Format: Journal Article
• Language: English
• Published: United States Rockefeller University Press 01.11.1991; The Rockefeller University Press
• Subjects: Animals; Calcium; Calcium - pharmacology; Cartilage; Cartilage - cytology; Cell culture techniques; Cell Division; Cells; Cells, Cultured; Chick Embryo; Chondrocytes; collagen; Collagen - biosynthesis; Collagens; Cultured cells; DNA; Electrophoresis, Polyacrylamide Gel; Embryos; Epiphyses; Kinetics; Tritium
• ISSN: 0021-9525; 1540-8140
• DOI: 10.1083/jcb.115.4.1171

Chondrocytes at different stages of cellular differentiation were isolated from the tarsal element (immature chondrocytes) and zones 2 and 3 (mature chondrocytes) of 12-d chick embryo tibiotarsus. The chondrocytes from the two sources differed in their cell morphologies, growth rate and production of type X collagen. In 24 h, zone 2 and 3 chondrocytes synthesized 800 times more type X collagen than tarsal chondrocytes. The effect of exogenous CaCl2(5 and 10 mM) on the synthesis of type X collagen by both mature and immature chondrocytes was tested. After a 72-h incubation of zone 2 and 3 chondrocytes with CaCl2type X collagen increased 8-fold with 5 mM and 10-fold with 10 mM Ca2+. [3H]Proline incorporation into culture medium and matrix macromolecules increased 11 and 32% with 5 and 10 mM CaCl2, respectively. Type II collagen synthesis was not affected by elevated extracellular CA2+during this 72-h period. Similar studies with tarsal chondrocytes demonstrated a time- and dose-dependent response to CaCl2with type X collagen levels reaching a 4-fold and 15-fold increase over controls with 5 and 10 mM Ca2+, respectively, at 48 h. Elevated extracellular Ca2+had no effect on cell proliferation. These observations offer the first direct evidence of the induction of type X collagen synthesis with elevated extracellular Ca2+.