Mechanism for the secretion of phosphaturic hormone FGF23 to blood

FGF 23是一种由骨产生的磷酸尿激素，通过增加尿磷酸盐排泄在肾脏中发挥作用。虽然FGF23被认为是一种激素，但其血液水平的调节机制仍不清楚。据报道，用双膦酸盐（一种骨吸收抑制剂）治疗与骨生成障碍患者中FGF 23水平的增加相关。因此，在本研究中，我们通过动物实验验证了由骨细胞产生的FGF 23储存在骨基质中，并随着骨细胞骨吸收而释放到循环中的假设。对小鼠施用刺激骨吸收的因子导致血清FGF 23水平增加，表明骨细胞骨吸收参与FGF 23向血液的分泌。

FGF23 is a phosphaturic hormone which is produced by bone and exerts its effects in kidney by increasing the urinary phosphate excretion. Although FGF23 is considered as a hormone, the mechanism for the regulation of its blood levels remains unclear. It is reported that treatment with a bisphosphonate, an inhibitor of bone resorption, is associated with increased levels of FGF23 in patients with osteogenesis imperfecta. Therefore, in the current study, we have tested the hypothesis by animal experiments that FGF23 produced by osteocytes is stored in bone matrix, and released to circulation in association with osteoclastic bone resorption. Administration of factors which stimulate bone resorption to mice resulted in the increased levels of serum FGF23, suggesting that osteoclastic bone resorption is involved in the secretion of FGF23 to blood.