[Role of the type 3 sodium-dependent phosphate transporter in the calcification of growth plate chondrocytes].

Phosphate is a second most abundant mineral next to calcium. The facts that hypophosphatemia is associated with the retardation of skeletal development and phosphate levels increase during endochondral ossification suggest that phosphate plays a role in cartilage differentiation. The type 3 sodium-dependent phosphate transporter (NPT3) expressed in growth plate chondrocytes transports extracellular phosphates into the cells. These phosphates are utilized for ATP synthesis, which in turn promotes apoptosis of growth plate chondrocytes through activation of the caspase signal pathways. Subsequently, matrix vesicles released from apoptotic chondrocytes accelerate calcification of chondrocytes. Our results suggest that phosphate plays a critical role in terminal differentiation of chondrocytes.