Phosphorylation of rat kidney Na-K pump at Ser938 is required for rapid angiotensin II-dependent stimulation of activity and trafficking in proximal tubule cells.
Phosphorylation of rat kidney Na-K pump at Ser938 is required for rapid angiotensin II-dependent stimulation of activity and trafficking in proximal tubule cells.
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DOI：
10.1152/ajpcell.00113.2015
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发表时间：
2016-02
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通讯作者：
Katherine J. Massey;Quanwen Li;N. Rossi;Susan M. Keezer;R. Mattingly;D. Yingst
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文献类型：
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作者：
Katherine J. Massey;Quanwen Li;N. Rossi;Susan M. Keezer;R. Mattingly;D. Yingst
血管紧张素（ANG）II如何剧烈刺激近端小管中的Na-K泵仅部分了解，限制了对ANG II如何升高血压的深入了解。首先，我们测试了ANG II是否在快速激活的条件下增加原生大鼠近端小管质膜中的泵的数量。我们发现，暴露于100 pM ANG II 2分钟（之前已证明可增加Na-K泵对Na的亲和力并将活性刺激三倍），可使天然小管质膜中Na-K泵的量增加33%。其次，我们测试了先前观察到的Na-K泵在Ser（938）处磷酸化的增加是否是刺激机制的一部分。这些实验是在负鼠肾细胞、稳定共表达ANG 1型（AT 1）受体的培养近端小管以及大鼠肾Na-K泵的野生型或S938 A突变体中进行的，实验条件是其他人发现的刺激活性的条件。我们发现，在10 pMANG II中孵育10 min可刺激野生型泵的活性从2.3 nmol K · mg protein（-1）· min（-1）增加到3.5 nmol K · mg protein（-1）· min（-1），并使质膜中的泵量增加80%，但对表达S938 A突变体的细胞没有影响。我们的结论是，急性刺激天然大鼠近端小管的钠钾泵活性包括增加运输到质膜和丝氨酸（938）的磷酸化是机制的一部分，血管紧张素II直接刺激活性和大鼠肾钠钾泵在负鼠肾细胞的运输。
How angiotensin (ANG) II acutely stimulates the Na-K pump in proximal tubules is only partially understood, limiting insight into how ANG II increases blood pressure. First, we tested whether ANG II increases the number of pumps in plasma membranes of native rat proximal tubules under conditions of rapid activation. We found that exposure to 100 pM ANG II for 2 min, which was previously shown to increase affinity of the Na-K pump for Na and stimulate activity threefold, increased the amount of the Na-K pump in plasma membranes of native tubules by 33%. Second, we tested whether previously observed increases in phosphorylation of the Na-K pump at Ser(938) were part of the stimulatory mechanism. These experiments were carried out in opossum kidney cells, cultured proximal tubules stably coexpressing the ANG type 1 (AT1) receptor, and either wild-type or a S938A mutant of rat kidney Na-K pump under conditions found by others to stimulate activity. We found that 10 min of incubation in 10 pM ANG II stimulated activity of wild-type pumps from 2.3 to 3.5 nmol K · mg protein(-1) · min(-1) and increased the amount of the pump in the plasma membrane by 80% but had no effect on cells expressing the S938A mutant. We conclude that acute stimulation of Na-K pump activity in native rat proximal tubules includes increased trafficking to the plasma membrane and that phosphorylation at Ser(938) is part of the mechanism by which ANG II directly stimulates activity and trafficking of the rat kidney Na-K pump in opossum kidney cells.