Zheng Wencui, Verlander Jill W, Lynch I Jeanette, Cash Melanie, Shao Jiahong, Stow Lisa R, Cain Brian D, Weiner I David, Wall Susan M, Wingo Charles S
North Florida/South Georgia Veterans Health System, USA.
Am J Physiol Renal Physiol. 2007 Jan;292(1):F456-66. doi: 10.1152/ajprenal.00087.2006. Epub 2006 Aug 8.
Mechanisms of K(+) secretion and absorption along the collecting duct are not understood fully. Because KCNQ1 participates in K(+) secretion within the inner ear and stomach, distribution of KCNQ1 in mouse kidney was studied using Northern and Western analyses, RT-PCR of isolated tubules, and immunohistochemistry. Northern blots demonstrated KCNQ1 transcripts in whole kidney. RT-PCR showed KCNQ1 mRNA in isolated distal convoluted tubule (DCT), connecting segment (CNT), collecting ducts (CD), and glomeruli. Immunoblots of kidney and stomach revealed a approximately 75-kDa protein, the expected mobility for KCNQ1. KCNQ1 was detected by immunohistochemistry throughout the distal nephron and CD. Thick ascending limbs exhibited weak basolateral immunolabel. In DCT and CNT cells, immunolabel was intense and basolateral, although KCNQ1 label was stronger in late than in early DCT. Initial collecting tubule and cortical CD KCNQ1 immunolabel was predominantly diffuse, but many cells exhibited discrete apical label. Double-labeling experiments demonstrated that principal cells, type B intercalated cells, and a few type A intercalated cells exhibited distinct apical KCNQ1 immunolabel. In inner medullary CD, principal cells exhibited distinct basolateral KCNQ1 immunolabel, whereas intercalated cells showed diffuse cytoplasmic staining. Thus KCNQ1 protein is widely distributed in mouse distal nephron and CD, with significant axial and cellular heterogeneity in location and intensity. These findings suggest that KCNQ1 has cell-specific roles in renal ion transport and may participate in K(+) secretion and/or absorption along the thick ascending limb, DCT, connecting tubule, and CD.
沿集合管的钾离子分泌和重吸收机制尚未完全明确。由于KCNQ1参与内耳和胃内的钾离子分泌，因此运用Northern印迹法和蛋白质免疫印迹法、分离肾小管的逆转录-聚合酶链反应（RT-PCR）以及免疫组织化学技术，对KCNQ1在小鼠肾脏中的分布进行了研究。Northern印迹法显示全肾中有KCNQ1转录本。RT-PCR表明在分离出的远曲小管（DCT）、连接段（CNT）、集合管（CD）和肾小球中有KCNQ1信使核糖核酸（mRNA）。肾脏和胃的免疫印迹显示有一种约75 kDa的蛋白质，这是KCNQ1预期的迁移率。通过免疫组织化学在整个远端肾单位和集合管中检测到了KCNQ1。髓袢升支粗段显示出较弱的基底外侧免疫标记。在DCT和CNT细胞中，免疫标记强烈且位于基底外侧，尽管晚期DCT中的KCNQ1标记比早期DCT更强。初始集合小管和皮质集合管的KCNQ1免疫标记主要呈弥漫性，但许多细胞呈现离散的顶端标记。双重标记实验表明，主细胞、B型闰细胞和少数A型闰细胞呈现出明显的顶端KCNQ1免疫标记。在内髓集合管中，主细胞呈现出明显的基底外侧KCNQ1免疫标记，而闰细胞显示出弥漫性的细胞质染色。因此，KCNQ1蛋白广泛分布于小鼠远端肾单位和集合管中，在位置和强度上存在显著的轴向和细胞异质性。这些发现表明，KCNQ1在肾离子转运中具有细胞特异性作用，可能参与沿髓袢升支粗段、DCT、连接小管和集合管的钾离子分泌和/或重吸收。
