View article

The regulation of the phosphaturic factor fibroblast growth factor 23 (FGF23) is not well understood. It was found that administration of 1, 25-dihydroxyvitamin D 3 (1, 25 [OH] 2 D 3) to mice rapidly increased serum FGF23 concentrations from a basal level of 90.6±8.1 to 213.8±14.6 pg/ml at 8 h (mean±SEM; P< 0.01) and resulted in a four-fold increase in FGF23 transcripts in bone, the predominate site of FGF23 expression. In the Hyp-mouse homologue of X-linked hypophosphatemic rickets, administration of 1, 25 (OH) 2 D 3 further increased circulating FGF23 levels. In Gcm2 null mice, low 1, 25 (OH) 2 D 3 levels were associated with a three-fold reduction in FGF23 levels that were increased by administration of 1, 25 (OH) 2 D 3. In osteoblast cell cultures, 1, 25 (OH) 2 D 3 but not calcium, phosphate, or parathyroid hormone stimulated FGF23 mRNA levels and resulted in a dose-dependent increase in FGF23 …