| Theme |
Osteocyte |
| Title |
Osteocytes and phosphate metabolism |
| Author |
Sawako Tatsumi |
Department of Molecular Nutrition, Institution of Health Biosciences, The University of Tokushima Graduate School |
| Author |
Hiroko Segawa |
Department of Molecular Nutrition, Institution of Health Biosciences, The University of Tokushima Graduate School |
| Author |
Mikiko Ito |
Department of Molecular Nutrition, Institution of Health Biosciences, The University of Tokushima Graduate School |
| Author |
Ken-ichi Miyamoto |
Department of Molecular Nutrition, Institution of Health Biosciences, The University of Tokushima Graduate School |
| [ Summary ] |
Osteocytes are terminally differentiated from osteoblasts. However, their functions are not understood, despite many years of study. Inorganic phosphate (Pi) re-absorption in the renal proximal tube is a major mechanism to maintain overall phosphate homeostasis. Fibroblast growth factor 23 (FGF23), a circulating phosphaturic hormone, regulates renal re-absorption of Pi. Overproduction of FGF23 due to tumors or mutations causes hypophosphatemic rickets / osteomalacia. A similar phenotype is also observed in individuals with inactivating mutations of the dentine matrix protein 1 (DMP1) or the phosphate-regulating gene, with homologies to endopeptidase on the X (PHEX). The three genes (FGF23, DMP1 and PHEX) are predominantly expressed in osteocytes. Thus, it has been proposed that DMP1 and PHEX are negative regulators of FGF23 found in osteocytes. Osteocytes can play an important role in phosphate metabolism of whole organisms. |