Regulation of intestinal phosphate transport -: I.: Segmental expression and adaptation to low-Pi diet of the type IIb Na+-Pi cotransporter in mouse small intestine
Regulation of intestinal phosphate transport -: I.: Segmental expression and adaptation to low-Pi diet of the type IIb Na+-Pi cotransporter in mouse small intestine
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DOI：
10.1152/ajpgi.00167.2004
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发表时间：
2005-03-01
影响因子：
4.5
通讯作者：
Biber, J
中科院分区：
文献类型：
--
作者：
Radanovic, T;Wagner, CA;Biber, J
Na+-P-i共转运蛋白NaPi-IIb （SLC34A2）参与小鼠小肠对P-i的吸收，并受多种激素和代谢因子的调节。然而，到目前为止，NaPi-llb在小肠中可能的节段性表达尚未得到解决。在这里，我们描述了NaPi-IIb共转运蛋白在小鼠小肠回肠中高度丰富，而在十二指肠和空肠中几乎不存在。Na+-P-i共转运研究与孤立的刷状边界膜证实，NaPi-IIb共转运在回肠中最高。在空肠和回肠中均观察到低磷酸盐饮食上调了NaPi-IIb和NaPi-IIb的共转运。此外，有证据表明，低磷酸盐饮食可引起整个小肠中NaPi-IIb mRNA丰度的增加。这些数据表明，在小鼠小肠中，磷酸盐是通过回肠中的钠离子依赖途径经细胞吸收的，而在十二指肠和空肠中，这一途径的重要性最小。此外，我们得出结论，在整个小鼠小肠中，低磷酸盐饮食影响NaPi-IIb mRNA的转录和/或稳定性。
The Na+-P-i cotransporter NaPi-IIb (SLC34A2) has been described to be involved in mouse small intestinal absorption of P-i and to be regulated by a number of hormones and metabolic factors. However, a possible segmental expression of NaPi-llb in small intestine has not been addressed so far. Here, we describe that the NaPi-IIb cotransporter is highly abundant in the ileum of mouse small intestine, whereas it is almost absent in the duodenum and in the jejunum. Na+-P-i cotransport studies with isolated brush border membranes confirmed that NaPi-IIb cotransport is highest in the ileum. Upregulation by a low-phosphate diet of NaPi-IIb and NaPi-IIb cotransport was observed both in the jejunum and the ileum. Furthermore, evidence is provided that a low-phosphate diet provokes an increase of the NaPi-IIb mRNA abundance along the entire small intestine. These data suggest that in mouse small intestine, phosphate is absorbed transcellulary by an Na+-dependent pathway in the ileum, whereas in the duodenum and jejunum, this pathway is of minimal importance. Furthermore, we conclude that along the entire mouse small intestine, low-phosphate diet affects transcription and/or the stability of NaPi-IIb mRNA.