Cell-specific expression of epithelial sodium channel alpha, beta, and gamma subunits in aldosterone-responsive epithelia from the rat: localization by in situ hybridization and immunocytochemistry.
Cell-specific expression of epithelial sodium channel alpha, beta, and gamma subunits in aldosterone-responsive epithelia from the rat: localization by in situ hybridization and immunocytochemistry.
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DOI：
10.1083/jcb.127.6.1907
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发表时间：
1994-12
期刊：
影响因子：
--
通讯作者：
Rossier BC
中科院分区：
文献类型：
--
作者：
Duc C;Farman N;Canessa CM;Bonvalet JP;Rossier BC
来自大鼠结肠的高选择性、阿米洛利敏感性上皮钠通道（rENaC）由称为α、β和γ rENaC的三个同源亚基组成，已通过功能表达克隆，并提出介导醛固酮响应性上皮中的产电钠重吸收。为了确定是否rENaC可以占钠吸收在体内，我们研究了细胞定位的钠通道信使RNA亚基的原位杂交和它们的细胞和亚细胞分布的免疫细胞化学在肾脏，结肠，唾液和汗腺的大鼠。在肾脏中，我们发现这三种亚基mRNA在肾远曲小管（DCT）、连接小管（CNT）、皮质集合管（CCD）和外髓集合管（OMCD）中特异性共表达，但在内髓集合管（IMCD）中不表达。我们证明了共同定位的α，β和γ亚基蛋白质的顶端膜的CCD和OMCD的大多数细胞。我们的数据表明，α，β和γ亚基mRNA和蛋白质在远端肾单位（IMCD除外）共表达，这与先前描述的阿米洛利敏感性产电钠转运的生理表达相关。然而，我们的数据表明，另一种钠转运蛋白介导IMCD中的产电阿米洛利敏感性钠重吸收。我们还将rENaC定位于远端结肠的表面上皮细胞以及唾液腺和汗腺的分泌管，提供了与以下假设一致的进一步证据：高度选择性的阿米洛利敏感性钠通道在醛固酮反应细胞中生理表达。
A highly selective, amiloride-sensitive, epithelial sodium channel from rat colon (rENaC), composed of three homologous subunits termed alpha, beta, and gamma rENaC, has been cloned by functional expression and was proposed to mediate electrogenic sodium reabsorption in aldosterone- responsive epithelia. To determine whether rENaC could account for sodium absorption in vivo, we studied the cellular localization of the sodium channel messenger RNA subunits by in situ hybridization and their cellular and subcellular distribution by immunocytochemistry in the kidney, colon, salivary, and sweat glands of the rat. In the kidney, we show that the three subunit mRNAs are specifically co- expressed in the renal distal convoluted tubules (DCT), connecting tubules (CNT), cortical collecting ducts (CCD), and outer medullary collecting ducts (OMCD), but not in the inner medullary collecting ducts (IMCD). We demonstrate co-localization of alpha, beta, and gamma subunit proteins in the apical membrane of a majority of cells of CCD and OMCD. Our data indicate that alpha, beta, and gamma subunit mRNAs and proteins are co-expressed in the distal nephron (excepting IMCD), a localization that correlates with the previously described physiological expression of amiloride-sensitive electrogenic sodium transport. Our data, however, suggest that another sodium transport protein mediates electrogenic amiloride-sensitive sodium reabsorption in IMCD. We also localized rENaC to the surface epithelial cells of the distal colon and to the secretory ducts of the salivary gland and sweat gland, providing further evidence consistent with the hypothesis that the highly selective, amiloride-sensitive sodium channel is physiologically expressed in aldosterone-responsive cells.