Decrease in cytosolic free Ca2+ and enhanced proteoglycan synthesis induced by cartilage derived growth factors in cultured chondrocytes.
Cartilage-derived growth factors, enhance proteoglycan synthesis in cultured chick-embryo chondrocytes, and have almost no effect on cell proliferation. Addition of cartilage derived growth factors to cartilage cells loaded with the fluorescent Ca2+ indicator quin 2, caused a rapid, concentration dependent decrease in cytoplasmic free Ca2+. This decrease persisted also in Ca2+-free medium, indicating that it is not mediated by a decrease in the passive permeability of cell membrane to Ca2+. Addition of the Ca2+ ionophore A23187, with or without cartilage derived factors, caused an increase in cytoplasmic free Ca2+ together with inhibition of proteoglycan synthesis and enhanced cell proliferation. The results may indicate that whereas cell proliferation in chondrocytes is signaled by an increase in cytoplasmic Ca2+ ([Ca2+]in), proteoglycan synthesis is signaled by a decrease in [Ca2+]in. The data lead to suggesting a mechanism for antagonistic regulation of cell proliferation and the expression of the differentiated state.
D000818:Animals; D000001:Calcimycin / Q000494:pharmacology; D002118:Calcium / Q000378:metabolism*; D002454:Cell Differentiation / Q000187:drug effects; D002455:Cell Division / Q000187:drug effects; D002463:Cell Membrane Permeability / Q000187:drug effects; D002478:Cells, Cultured; D002642:Chick Embryo; D003600:Cytosol / Q000378:metabolism; D006025:Glycosaminoglycans / Q000096:biosynthesis; D006132:Growth Plate / Q000187:drug effects / Q000196:embryology / Q000378:metabolism*; D006133:Growth Substances / Q000494:pharmacology*; D011506:Proteins / Q000494:pharmacology*; D011509:Proteoglycans / Q000096:biosynthesis*; D051381:Rats
D006025:Glycosaminoglycans; D006133:Growth Substances; D011506:Proteins; D011509:Proteoglycans; D000001:Calcimycin; D002118:Calcium