1) Molecular Mechanisms Underlying the Skeletal Development

　　In vertebrates, the skeleton develops through two distinct pathways; membranous bone formation (e.g., calvarium) and endochondral bone formation (e.g., limbs and vertebrae). In membranous bone formation, osteoblasts of mesenchymal origin directly form bones. On the other hand, in endochondral bone formation, bone develops through the cartilageous intermediates formed by chondrocytes. Although various molecules have been identified to be involved in these processes, the mechanisms for osteoblasts/chondrocytes maturation are still not fully understood.
　　We are currently investigating the molecular mechanisms underlying osteoblasts/chondrocytes differentiation and mineralization using cellular and molecular approaches.

2) Molecular Mechanisms that Regulate Phosphate Homeostasis

　　An adult human contains approximately 600 g of phosphorus. Some 85% of this phosphorus is present in the skeleton as the crystalline form.
　　The extracellular pool of orthophosphate is approximately 550 mg, and in dynamic equilibrium with phosphate entry and exit via the intestine, bone, kidney, and soft tissues. The kidney plays the dominant role in regulating phosphate homeostasis through reabsorption of inorganic phosphate in the proximal tubules.
　　We are attempting to clarify the molecular mechanisms that regulate the renal phosphate reabsorption.