Intestinal Na-Pi cotransporter adaptation to dietary Pi content in vitamin D receptor null mice
Intestinal Na-Pi cotransporter adaptation to dietary Pi content in vitamin D receptor null mice
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DOI：
10.1152/ajprenal.00375.2003
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发表时间：
2004-07-01
影响因子：
4.2
通讯作者：
Miyamoto, K
中科院分区：
文献类型：
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作者：
Segawa, H;Kaneko, I;Miyamoto, K
最近的研究表明，维生素 D 可能在肠道 Na(+) 依赖性磷酸盐转运适应不同膳食 Pi 水平的过程中发挥作用。因此，本研究的目标是评估转基因小鼠中 Na(+) 依赖性 P(i) 共转运活性，以确定维生素 D 是否是该过程的重要介质。与野生型 (VDR+/+) 小鼠相比，维生素 D 受体 (VDR) 缺失 [VDR (-/-)] 小鼠的肠刷状缘膜 (BBM)、Na(+) 依赖性 P(i) 共转运活性显着降低。虽然 VDR (-/-) 和 VDR (+/+) 小鼠中肠道 Na-P(i) 协同转运蛋白（IIb 型）mRNA 水平相似，但与 VDR (+/+) 小鼠相比，VDR (-/-) 小鼠中 IIb 型 Na-P(i) 协同转运蛋白表达显着受到抑制。此外，VDR (-/-) 和 VDR (+/+) 小鼠肾 BBM 中的 Na-P(i) 协同转运活性相似，但 VDR (-/-) 小鼠中 IIa 型 Na-P(i) 协同转运蛋白表达降低。给予低P（i）饮食后，VDR（+/+）和VDR（-/-）小鼠的IIb型蛋白表达显着增加，并且VDR（-/-）小鼠的肠道BBM中存在IIb型蛋白表达。这些数据表明，肠道 Na-P(i) 共转运对低 P(i) 饮食的适应与维生素 D 无关。
Recent studies suggest that vitamin D may play a role in intestinal Na(+)-dependent phosphate transport adaptation to variable levels of dietary Pi. Therefore, the goal of the current study was to assess Na(+)-dependent P(i) cotransport activity in transgenic mice to determine whether vitamin D is an essential mediator of this process. Intestinal brush-border membrane (BBM), Na(+)-dependent P(i) cotransport activity was significantly decreased in vitamin D receptor (VDR) null [VDR (-/-)] mice compared with wild-type (VDR+/+) mice. While intestinal Na-P(i) cotransporter (type IIb) mRNA levels were similar in VDR (-/-) and VDR (+/+) mice, type IIb Na-P(i) cotransporter protein expression was markedly suppressed in VDR (-/-) mice compared with VDR (+/+) mice. Furthermore, Na-P(i) cotransport activity in renal BBM was similar in VDR (-/-) and VDR (+/+) mice, but type IIa Na-P(i) cotransporter protein expression was decreased in VDR (-/-) mice. After administration of a low-P(i) diet, type IIb protein expression was significantly increased in VDR (+/+) and VDR (-/-) mice, and type IIb protein expression was present in the intestinal BBM of VDR (-/-) mice. These data demonstrate that intestinal Na-P(i) cotransport adaptation to a low-P(i) diet occurs independently of vitamin D.