TY - JOUR
T1 - Aberrant Phex function in osteoblasts and osteocytes alone underlies murine X-linked hypophosphatemia
AU - Yuan, Baozhi
AU - Takaiwa, Masanori
AU - Clemens, Thomas L.
AU - Feng, Jian Q.
AU - Kumar, Rajiv
AU - Rowe, Peter S.
AU - Xie, Yixia
AU - Drezner, Marc K.
PY - 2008/2/1
Y1 - 2008/2/1
N2 - Patients with X-linked hypophosphatemia (XLH) and the hyp-mouse, a model of XLH characterized by a deletion in the Phex gene, manifest hypophosphatemia, renal phosphate wasting, and rickets/osteomalacia. Cloning of the PHEX/Phex gene and mutations in affected patients and hyp-mice established that alterations in PHEX/Phex expression underlie XLH. Although PHEX/Phex expression occurs primarily in osteoblast lineage cells, transgenic Phex expression in hyp-mouse osteoblasts fails to rescue the phenotype, suggesting that Phex expression at other sites underlies XLH. To establish whether abnormal Phex in osteoblasts and/or osteocytes alone generates the HYP phenotype, we created mice with a global Phex knockout (Cre-PhexΔflox/y mice) and conditional osteocalcin-promoted (OC-promoted) Phex inactivation in osteoblasts and osteocytes (OC-Cre-PhexΔflox/y). Serum phosphorus levels in Cre-PhexΔflox/y, OC-Cre-PhexΔflox/y, and hyp-mice were lower than those in normal mice. Kidney cell membrane phosphate transport in Cre-PhexΔflox/y, OC-Cre-Phex Δflox/y, and hyp-mice was likewise reduced compared with that in normal mice. Abnormal renal phosphate transport in Cre-Phex Δflox/y and OC-Cre-PhexΔflox/y mice was associated with increased bone production and serum FGF-23 levels and decreased kidney membrane type IIa sodium phosphate cotransporter protein, as was the case in hyp-mice. In addition, Cre-PhexΔflox/y, OC-Cre-Phex Δflox/y, and hyp-mice manifested comparable osteomalacia. These data provide evidence that aberrant Phex function in osteoblasts and/or osteocytes alone is sufficient to underlie the hyp-mouse phenotype.
AB - Patients with X-linked hypophosphatemia (XLH) and the hyp-mouse, a model of XLH characterized by a deletion in the Phex gene, manifest hypophosphatemia, renal phosphate wasting, and rickets/osteomalacia. Cloning of the PHEX/Phex gene and mutations in affected patients and hyp-mice established that alterations in PHEX/Phex expression underlie XLH. Although PHEX/Phex expression occurs primarily in osteoblast lineage cells, transgenic Phex expression in hyp-mouse osteoblasts fails to rescue the phenotype, suggesting that Phex expression at other sites underlies XLH. To establish whether abnormal Phex in osteoblasts and/or osteocytes alone generates the HYP phenotype, we created mice with a global Phex knockout (Cre-PhexΔflox/y mice) and conditional osteocalcin-promoted (OC-promoted) Phex inactivation in osteoblasts and osteocytes (OC-Cre-PhexΔflox/y). Serum phosphorus levels in Cre-PhexΔflox/y, OC-Cre-PhexΔflox/y, and hyp-mice were lower than those in normal mice. Kidney cell membrane phosphate transport in Cre-PhexΔflox/y, OC-Cre-Phex Δflox/y, and hyp-mice was likewise reduced compared with that in normal mice. Abnormal renal phosphate transport in Cre-Phex Δflox/y and OC-Cre-PhexΔflox/y mice was associated with increased bone production and serum FGF-23 levels and decreased kidney membrane type IIa sodium phosphate cotransporter protein, as was the case in hyp-mice. In addition, Cre-PhexΔflox/y, OC-Cre-Phex Δflox/y, and hyp-mice manifested comparable osteomalacia. These data provide evidence that aberrant Phex function in osteoblasts and/or osteocytes alone is sufficient to underlie the hyp-mouse phenotype.
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U2 - 10.1172/JCI32702
DO - 10.1172/JCI32702
M3 - Article
C2 - 18172553
AN - SCOPUS:38849170631
SN - 0021-9738
VL - 118
SP - 722
EP - 734
JO - Journal of Clinical Investigation
JF - Journal of Clinical Investigation
IS - 2
ER -