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Dysregulated gene expression in the primary osteoblasts and osteocytes isolated from hypophosphatemic Hyp mice.

Authors: Miyagawa, K  Yamazaki, M  Kawai, M  Nishino, J  Koshimizu, T  Ohata, Y  Tachikawa, K  Mikuni-Takagaki, Y  Kogo, M  Ozono, K  Michigami, T 
Citation: Miyagawa K, etal., PLoS One. 2014 Apr 7;9(4):e93840. doi: 10.1371/journal.pone.0093840. eCollection 2014.
Pubmed: (View Article at PubMed) PMID:24710520
DOI: Full-text: DOI:10.1371/journal.pone.0093840

Osteocytes express multiple genes involved in mineral metabolism including PHEX, FGF23, DMP1 and FAM20C. In Hyp mice, a murine model for X-linked hypophosphatemia (XLH), Phex deficiency results in the overproduction of FGF23 in osteocytes, which leads to hypophosphatemia and impaired vitamin D metabolism. In this study, to further clarify the abnormality in osteocytes of Hyp mice, we obtained detailed gene expression profiles in osteoblasts and osteocytes isolated from the long bones of 20-week-old Hyp mice and wild-type (WT) control mice. The expression of Fgf23, Dmp1, and Fam20c was higher in osteocytic cells than in osteoblastic cells in both genotypes, and was up-regulated in Hyp cells. Interestingly, the up-regulation of these genes in Hyp bones began before birth. On the other hand, the expression of Slc20a1 encoding the sodium/phosphate (Na+/Pi) co-transporter Pit1 was increased in osteoblasts and osteocytes from adult Hyp mice, but not in Hyp fetal bones. The direct effects of extracellular Pi and 1,25-dihydroxyvitamin D3 [1,25(OH)2D3] on isolated osteoblastic and osteocytic cells were also investigated. Twenty-four-hour treatment with 10-8 M 1,25(OH)2D3 increased the expression of Fgf23 in WT osteoblastic cells but not in osteocytic cells. Dmp1 expression in osteocytic cells was increased due to the 24-hour treatment with 10 mM Pi and was suppressed by 10-8 M 1,25(OH)2D3 in WT osteocytic cells. We also found the up-regulation of the genes for FGF1, FGF2, their receptors, and Egr-1 which is a target of FGF signaling, in Hyp osteocytic cells, suggesting the activation of FGF/FGFR signaling. These results implicate the complex gene dysregulation in osteoblasts and osteocytes of Hyp mice, which might contribute to the pathogenesis.

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CRRD Object Information
CRRD ID: 11560488
Created: 2016-11-08
Species: All species
Last Modified: 2016-11-08
Status: ACTIVE



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RGD is funded by grant HL64541 from the National Heart, Lung, and Blood Institute on behalf of the NIH.