Effect of vitamin D3 on proteoglycan degradation of growth cartilage

Degradation of proteoglycans in growth cartilage plays an important role during endochondral ossification. Degradation is controlled by certain enzymes secreted by macrophages. Vitamin D3 metabolites markedly enhance the degradation of proteoglycans by macrophages in vitro. However, this enhancing activity of D3 metabolites is eliminated when the growth cartilage cells are lysed with 0.2N NH4OH. Puromycin (10 micrograms/ml) also inhibits the enhancement effect. These results suggest that D3 metabolites stimulate the synthesis of a D3-dependent substance by growth cartilage cells and that subsequently this substance enhances the enzymatic degradation of proteoglycans by macrophages.