The main function of FGF23 seems to be regulation of phosphate concentration in plasma. FGF23 is secreted by osteocytes in response to elevated calcitriol. FGF23 acts on the kidneys, where it decreases the expression of NPT2, a sodium-phosphate cotransporter in the proximal tubule.[4] Thus, FGF23 decreases the reabsorption and increases excretion of phosphate. FGF23 may also suppress 1-alpha-hydroxylase, reducing its ability to activate vitamin D and subsequently impairing calcium absorption.[3][5]
Loss of FGF23 activity is thought to lead to increased phosphate levels and the clinical syndrome of familial tumor calcinosis. This gene was identified by its mutations associated with autosomal dominant hypophosphatemic rickets.[7]
History
Prior to its discovery in 2000, it was hypothesized that a protein existed which performed the functions subsequently shown for FGF23. This putative protein was known as phosphatonin.[8] Several types of effects were described including impairment of sodium dependent phosphate transport in both intestinal and renal brush border membrane vesicles, inhibition of production of calcitriol, stimulation of breakdown of calcitriol, and inhibition of production/secretion of parathyroid hormone.
References
↑Yamashita T, Yoshioka M, Itoh N (October 2000). "Identification of a novel fibroblast growth factor, FGF-23, preferentially expressed in the ventrolateral thalamic nucleus of the brain". Biochem. Biophys. Res. Commun. 277 (2): 494–8. doi:10.1006/bbrc.2000.3696. PMID11032749.
↑Fukumoto S (2008). "Physiological regulation and disorders of phosphate metabolism--pivotal role of fibroblast growth factor 23". Intern. Med. 47 (5): 337–43. doi:10.2169/internalmedicine.47.0730. PMID18310961.
↑ 3.03.1Perwad F (2007). "Fibroblast growth factor 23 impairs phosphorus and vitamin D metabolism in vivo and suppresses 25-hydroxyvitamin D-1alpha-hydroxylase expression in vitro". Am J Physiol Renal Physiol. 293 (5): F1577–83. doi:10.1152/ajprenal.00463.2006. PMID17699549.
Silve C, Beck L (2003). "Is FGF23 the long sought after phosphaturic factor phosphatonin?". Nephrol. Dial. Transplant. 17 (6): 958–61. doi:10.1093/ndt/17.6.958. PMID12032180.
Quarles LD (2003). "FGF23, PHEX, and MEPE regulation of phosphate homeostasis and skeletal mineralization". Am. J. Physiol. Endocrinol. Metab. 285 (1): E1–9. doi:10.1152/ajpendo.00016.2003. PMID12791601.
Fukagawa M, Nii-Kono T, Kazama JJ (2005). "Role of fibroblast growth factor 23 in health and in chronic kidney disease". Curr. Opin. Nephrol. Hypertens. 14 (4): 325–9. doi:10.1097/01.mnh.0000172717.49476.80. PMID15930999.
Imel EA, Econs MJ (2006). "Fibroblast growth factor 23: roles in health and disease". J. Am. Soc. Nephrol. 16 (9): 2565–75. doi:10.1681/ASN.2005050573. PMID16033853.
Econs MJ (2000). "Autosomal dominant hypophosphataemic rickets is associated with mutations in FGF23". Nat. Genet. 26 (3): 345–8. doi:10.1038/81664. PMID11062477.
White KE, Jonsson KB, Carn G, Hampson G, Spector TD, Mannstadt M, Lorenz-Depiereux B, Miyauchi A, Yang IM, Ljunggren O, Meitinger T, Strom TM, Jüppner H, Econs MJ (2001). "The autosomal dominant hypophosphatemic rickets (ADHR) gene is a secreted polypeptide overexpressed by tumors that cause phosphate wasting". J. Clin. Endocrinol. Metab. 86 (2): 497–500. doi:10.1210/jc.86.2.497. PMID11157998.
Bowe AE, Finnegan R, Jan de Beur SM, Cho J, Levine MA, Kumar R, Schiavi SC (2001). "FGF-23 inhibits renal tubular phosphate transport and is a PHEX substrate". Biochem. Biophys. Res. Commun. 284 (4): 977–81. doi:10.1006/bbrc.2001.5084. PMID11409890.
White KE, Carn G, Lorenz-Depiereux B, Benet-Pages A, Strom TM, Econs MJ (2002). "Autosomal-dominant hypophosphatemic rickets (ADHR) mutations stabilize FGF-23". Kidney Int. 60 (6): 2079–86. doi:10.1046/j.1523-1755.2001.00064.x. PMID11737582.
Kruse K, Woelfel D, Strom TM, Storm TM (2002). "Loss of renal phosphate wasting in a child with autosomal dominant hypophosphatemic rickets caused by a FGF23 mutation". Horm. Res. 55 (6): 305–8. doi:10.1159/000050018. PMID11805436.
Yamashita T, Konishi M, Miyake A, Inui K, Itoh N (2002). "Fibroblast growth factor (FGF)-23 inhibits renal phosphate reabsorption by activation of the mitogen-activated protein kinase pathway". J. Biol. Chem. 277 (31): 28265–70. doi:10.1074/jbc.M202527200. PMID12032146.
Saito H, Kusano K, Kinosaki M, Ito H, Hirata M, Segawa H, Miyamoto K, Fukushima N (2003). "Human fibroblast growth factor-23 mutants suppress Na+-dependent phosphate co-transport activity and 1alpha,25-dihydroxyvitamin D3 production". J. Biol. Chem. 278 (4): 2206–11. doi:10.1074/jbc.M207872200. PMID12419819.
Bai XY, Miao D, Goltzman D, Karaplis AC (2003). "The autosomal dominant hypophosphatemic rickets R176Q mutation in fibroblast growth factor 23 resists proteolytic cleavage and enhances in vivo biological potency". J. Biol. Chem. 278 (11): 9843–9. doi:10.1074/jbc.M210490200. PMID12519781.
Larsson T, Zahradnik R, Lavigne J, Ljunggren O, Jüppner H, Jonsson KB (2003). "Immunohistochemical detection of FGF-23 protein in tumors that cause oncogenic osteomalacia". Eur. J. Endocrinol. 148 (2): 269–76. doi:10.1530/eje.0.1480269. PMID12590648.
