Internalization of NKCC2 is impaired in thick ascending limb of Henle in moesin knockout mice
Internalization of NKCC2 is impaired in thick ascending limb of Henle in moesin knockout mice
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DOI：
10.1007/s00424-018-2134-z
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发表时间：
2018-07-01
影响因子：
4.5
通讯作者：
Asano, Shinji
中科院分区：
文献类型：
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作者：
Kawaguchi, Kotoku;Hatano, Ryo;Asano, Shinji
膜突蛋白在几种类型的细胞中表达，包括上皮细胞和内皮细胞。膜突蛋白在调节细胞运动和膜蛋白内化过程中起重要作用。然而，膜突蛋白在肾脏中的生理作用仍不清楚。在此，我们使用膜突蛋白基因敲除（Msn（-/y））小鼠研究了膜突蛋白在肾脏中的生理功能。Msn（-/y）小鼠肾脏形态未见明显异常。然而，我们发现，Msn（-/y）小鼠表现出轻度高尿酸血症，并降低肾小球滤过率相比，野生型（WT）小鼠。与WT小鼠相比，Msn（-/y）小鼠中NaCl的绝对电解质排泄没有显著变化。在肾髓质中，检测到膜突蛋白在厚的Henle升支（TALH），如以前报道的。为了确定膜突蛋白在TALH中的生理功能，我们检测了NKCC 2在Msn（-/y）小鼠中的表达和亚细胞定位。有趣的是，在Msn（-/y）小鼠中，NKCC 2的顶端表面表达水平而非总表达增加。肾髓质裂解物的亚细胞分级和使用肾小管悬浮液的内化测定显示NKCC 2内吞过程受损。由于在Msn（-/y）小鼠中NKCC 2在脂筏组分中的分布减少，膜突蛋白可能调节NKCC 2向微区的分布。这些结果表明，膜突蛋白调节NKCC 2的内化。此外，水负荷引起的正常水合作用导致Msn（-/y）小鼠低钠血症，表明膜突蛋白功能障碍与不适当抗利尿的肾源性综合征（NSIAD）有关。
Moesin is expressed in several types of cells including epithelial and endothelial cells. Several groups reported that moesin plays important roles in the regulation of the cellular motility, and the process of internalization of membrane proteins. However, the physiological roles of moesin in the kidney still remain unclear. Herein, we examined the physiological function of moesin in the kidney using moesin knockout (Msn (-/y) ) mice. There was no obvious abnormality in the renal morphology of Msn (-/y) mice. However, we found that Msn (-/y) mice exhibited mild hyperchloremia, and reduced glomerular filtration rate compared to wild type (WT) mice. Absolute electrolytes excretions of NaCl in Msn (-/y) mice were not significantly changed compared to WT mice. In the renal medulla, moesin was detected in thick ascending limb of Henle (TALH) as previously reported. To determine the physiological function of moesin in TALH, we examined the expression and subcellular localization of NKCC2 in Msn (-/y) mice. Interestingly, apical surface expression level, but not total expression of NKCC2 was increased in Msn (-/y) mice. Subcellular fractionation of renal medulla lysate and internalization assay using tubular suspension showed that the process of NKCC2 endocytosis is impaired. Since the distribution of NKCC2 in lipid raft fractions was decreased in Msn (-/y) mice, moesin may regulate the NKCC2 distribution to microdomain. These results suggest that moesin regulates the internalization of NKCC2. Furthermore, euhydration by water loading caused hyponatremina in Msn (-/y) mice, suggesting that dysfunction of moesin is associated with the nephrogenic syndrome of inappropriate antidiuresis (NSIAD).