EFFECT OF RETINOIC ACID ON PROLIFERATION AND DIFFERENTIATION OF CULTURED CHONDROCYTES IN TERMINAL DIFFERENTIATION

We obtained terminally differentiated chondrocytes in monolayer culture from chick embryonal growth plates, and examined the effect of retinoic acid on these cells. The cells treated with retinoic acid ceased type X collagen synthesis and showed decreased calcium incorporation into cell layers. Retinoic acid tended to stimulate proliferation of the cultured chondrocytes. It also increased DNA accumulation dose-dependently in the range from 1 nM to 1 μM. DNA synthesis in the growth phase and confluency was stimulated within 10 h after addition of 0.1 μM retinoic acid. [3H]Retinoic acid, binding, which was inhibited by simultaneous addition of excess unlabeled retinoic acid, was detected in both the cytosolic and nuclear fractions of the chondrocytes. The retinoic acid binding capacity of the nuclear fraction was increased by pretreating the cells with retinoic acid. These results indicate that rectinoic acid binds to both the cytosolic and nuclear fractions of cultured chondrocytes, and induces their proliferation and dedifferentiation. © 1990 COPYRIGHT, 1990 BY THE JOURNAL OF BIOCHEMISTRY.