The roles of vitamin D dependent novel phosphate sensing-system on calcium metabolism and local calcification.

2016 Fiscal Year Final Research Report

• Project/Area Number: 26462816
• Research Category: Grant-in-Aid for Scientific Research (C)
• Allocation Type: Multi-year Fund
• Section: 一般
• Research Field: Functional basic dentistry
• Research Institution: Nagasaki University
• Principal Investigator: MASUYAMA Ritsuko 長崎大学, 医歯薬学総合研究科(歯学系), 准教授 (60297596)
• Project Period (FY): 2014-04-01 – 2017-03-31
• Keywords: カルシウム輸送 / リン / 小腸 / 骨 / ビタミンD

Outline of Final Research Achievements

The impaired calcium absorption in intestinal Vdr null mice was improved by dietary phosphate restriction and resulted in increased bone mass, indicating that intestinal luminal phosphate levels influenced calcium absorption. Accordingly, transcellular calcium transport in cultured polarized intestinal epithelial cells was increased when apical side of cells were exposed to low extracellular phosphate levels (0.5 mM phosphate) compared to normal or high phosphate levels (1.0 and 5.0 mM). Mechanistically, low phosphate levels increased ATP contents at the apical extracellular side which stimulated the apical ATP receptor to promote calcium entry. The luminal ATP levels were regulated by the apical abundance of the ATP metabolizing enzyme, ectonucleotide pyrophosphatase/phosphodiesterase (ENPP1). Sub-cellular localization of ENPP1 was reduced when apical side of intestinal epithelial cells were exposed to low extracellular phosphate, and led to the increase in luminal ATP levels.

Free Research Field

骨代謝学、栄養学