Muller Y L, Collins J F, Ghishan F K
Department of Pediatrics, Steele Memorial Children's Research Center, University of Arizona Health Sciences Center, Tucson 85724, USA.
Pediatr Res. 1998 Nov;44(5):633-8. doi: 10.1203/00006450-199811000-00003.
X-linked hypophosphatemic (Hyp) rickets is characterized by short stature, rickets, and bone abnormalities. Biochemically, hypophosphatemia and decreased renal reabsorption of phosphate are the hallmark of the disorder. Mutation of the PEX gene has been linked to human and murine Hyp rickets. Our study showed that phenotypical changes of this disease could be detected in 6-wk-old mice, but not in 2-wk-old mice. Therefore, we developed a PCR method to identify Hyp mice by detecting a lack of the 3' region of the PEX gene. Serum inorganic phosphate (Pi) levels were decreased, whereas alkaline phosphatase activity was increased in 2- and 6-wk-old Hyp mice. Northern blot showed that renal Na(+)-Pi transporter mRNA levels were decreased by 2.1-fold (1.47 +/- 0.21 densitometric units for normals; 0.68 +/- 1.43 for Hyp mice; p < 0.040) in 2-wk-old Hyp mice and by 1.7-fold (2.41 +/- 0.42 for normals; 1.44 +/- 0.33 for Hyp mice; p < 0.027) in 6-wk-old mice. Western blot showed that levels of immunoreactive renal Na(+)-Pi transporter protein were decreased by 4.5-fold (0.90 +/- 0.10 for normals; 0.22 +/- 0.08 for Hyp mice; p < 0.001) in 2-wk-old Hyp mice; and by 4.9-fold (1.47 +/- 0.19 for normals; 0.30 +/- 0.09 for Hyp mice; p < 0.0001) in 6-wk-old Hyp mice. In addition, levels of Na(+)-Pi transporter mRNA and protein were increased between 2- and 6-wk-old normal mice, but not in Hyp mice. This study demonstrates an easy assay to detect Hyp mutation and characterizes the defect during ontogeny of the Na(+)-Pi transporter in Hyp mice.
X连锁低磷血症（Hyp）佝偻病的特征为身材矮小、佝偻病和骨骼异常。在生物化学方面，低磷血症和肾脏对磷酸盐重吸收减少是该疾病的标志。PEX基因突变已与人类和小鼠的Hyp佝偻病相关联。我们的研究表明，这种疾病的表型变化在6周龄小鼠中可以检测到，但在2周龄小鼠中未检测到。因此，我们开发了一种聚合酶链反应（PCR）方法，通过检测PEX基因3'区域的缺失来鉴定Hyp小鼠。在2周龄和6周龄的Hyp小鼠中，血清无机磷酸盐（Pi）水平降低，而碱性磷酸酶活性升高。Northern印迹显示，2周龄Hyp小鼠肾脏钠-磷转运体mRNA水平降低了2.1倍（正常小鼠为1.47±0.21光密度单位；Hyp小鼠为0.68±1.43；p<0.040），6周龄小鼠降低了1.7倍（正常小鼠为2.41±0.42；Hyp小鼠为1.44±0.33；p<0.027）。Western印迹显示，2周龄Hyp小鼠中免疫反应性肾脏钠-磷转运体蛋白水平降低了4.5倍（正常小鼠为0.90±0.10；Hyp小鼠为0.22±0.08；p<0.001）；6周龄Hyp小鼠降低了4.9倍（正常小鼠为1.47±0.19；Hyp小鼠为0.30±0.09；p<0.0001）。此外，在2周龄至6周龄的正常小鼠中，钠-磷转运体mRNA和蛋白水平升高，但在Hyp小鼠中未升高。本研究证明了一种检测Hyp突变的简便方法，并对Hyp小鼠中钠-磷转运体个体发育过程中的缺陷进行了特征描述。
