Phex mutation causes overexpression of FGF23 in teeth.
OBJECTIVE
Hyp mice have a disorder in phosphate homeostasis, and display hypo-mineralization in bones and teeth, while the Phex (phosphate regulating gene homologies to endopeptidase on the X chromosome) gene in Hyp mice has a deletion of the 3' end. We investigated whether a mutation of Phex has an effect on the expression level of fibroblast growth factor 23 (FGF23), one of the key factors of phosphate homeostasis, in developing teeth of Hyp mice.


METHODS
RT-PCR and in situ hybridisation analyses for FGF23 were performed using developing teeth of WT mice. Quantitative RT-PCR analyses for FGF23 were performed using the tooth germs of WT and Hyp mice in both in vivo and in vitro experiments.


RESULTS
Undifferentiated and early secretory ameloblasts as well as odontoblasts expressed FGF23 mRNA during early tooth development. Further, quantitative RT-PCR analyses revealed that the amount of FGF23 mRNA in Hyp mouse teeth was significantly higher than that in wild type mice.


CONCLUSIONS
These findings suggest that loss of Phex function is related to overexpression of FGF23 in teeth, which is an intrinsic defect of Hyp mouse teeth.
Onishi
T
T
Department of Pediatric Dentistry, Osaka University Graduate School of Dentistry, 1-8 Yamadaoka, Suita, Osaka 565-0871, Japan.
Umemura
S
S
Shintani
S
S
Ooshima
T
T
D000818:Animals; D015519:Bone Density / Q000235:genetics; D002113:Calcification, Physiologic; D000089703:Fibroblast Growth Factor-23; D005346:Fibroblast Growth Factors / Q000378:metabolism*; D015870:Gene Expression; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D009154:Mutation / Q000235:genetics*; D053402:PHEX Phosphate Regulating Neutral Endopeptidase / Q000097:blood / Q000235:genetics*; D014070:Tooth / Q000378:metabolism*; D014076:Tooth Diseases / Q000235:genetics*
C000717428:Fgf23 protein, mouse; D005346:Fibroblast Growth Factors; D000089703:Fibroblast Growth Factor-23; D053402:PHEX Phosphate Regulating Neutral Endopeptidase; C506232:Phex protein, mouse