Submitted on March 18, 2009
Revised on June 10, 2009
Accepted on June 23, 2009
Human PTH gene regulation in vivo using transgenic mice
Vardit Lavi-Moshayoff1, Justin Silver1, and Tally Naveh-Many1*
1 Hadassah Hebrew University Medical Center
* To whom correspondence should be addressed. E-mail: tally{at}cc.huji.ac.il.
To study the regulation of the human PTH (hPTH) gene in vivo we created transgenic mice with the hPTH gene expressed in the mouse parathyroid, using a bacterial artificial chromosome (BAC) containing the hPTH gene within its 144 kb chromosomal region. The BAC construct maintains the native hPTH gene surrounding sequences and isolates it from positional effects. The transgenic mice had normal levels of serum mouse PTH (mPTH) in addition to both intact and bioactive hPTH. Despite the presence of both mPTH and hPTH, serum calcium and 1,25(OH)2 vitamin D levels were normal. The lack of response to hPTH may be due to tachyphylaxis of the mPTH receptor (PTH1R) and/or impaired recognition of the mPTH1R. In contrast, the regulation of hPTH levels in the mouse was intact. A calcium depleted diet increased serum mPTH and both intact and bioactive hPTH. mPTH and hPTH mRNA levels were also markedly increased. The calcimimetic R568 dramatically decreased mPTH and hPTH serum levels. Administered recombinant fibroblast growth factor 23 (FGF23) decreased hPTH. Therefore, the regulation of hPTH gene expression and serum hPTH levels is intact in the transgenic mice, indicating preservation of the signal transduction of the parathyroid calcium receptor and the Klotho-FGF receptor between mouse and man.
