Expression of a novel isoform of Na(+)/H(+) exchanger 3 in the kidney and intestine of banded houndshark, Triakis scyllium.
Expression of a novel isoform of Na(+)/H(+) exchanger 3 in the kidney and intestine of banded houndshark, Triakis scyllium.
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DOI：
10.1152/ajpregu.00417.2012
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发表时间：
2013-05
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通讯作者：
Shanshan Li;A. Kato;S. Takabe;Anping Chen;M. Romero;Takahiro Umezawa;Tsutomu Nakada;S. Hyodo;S. Hirose
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文献类型：
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作者：
Shanshan Li;A. Kato;S. Takabe;Anping Chen;M. Romero;Takahiro Umezawa;Tsutomu Nakada;S. Hyodo;S. Hirose
Na（+）/H（+）交换器3（NHE 3）是哺乳动物肠道和肾脏吸收Na（+）的主要途径之一，近年来对水生脊椎动物（硬骨鱼和板鳃类）的研究表明，NHE 3在鳃中表达，并在离子和酸碱调节中发挥重要作用。为了了解NHE 3在板鳃类神经调节器官中的作用，我们分析了NHE 3在海洋板鳃类，日本带状角鲨（Triakis scarpus）的肾脏和肠道的表达和定位。Triakis NHE 3的mRNA在鳃、肾、螺旋肠和直肠中表达最高。肾和肠表达NHE 3的转录异构体（NHE 3 k/i），其与从鳃分离的NHE 3（NHE 3g）相比具有不同的氨基末端，这表明NHE 3 k/i和NHE 3g通过交替启动子使用由单个基因产生。Triakis肾的免疫组织化学分析表明，NHE 3 k/i表达在窦区的近端和远端小管的一部分的顶膜。在肾的束区，NHE 3 k/i在称为稀释段的早期远端小管的顶膜中表达。在螺旋肠和直肠中，NHE 3 k/i定位于上皮细胞的顶膜。当Triakis在130%海水中驯化时，肾脏中NHE 3 k/i的转录水平增加，而在螺旋肠中的转录水平增加，在稀释海水中驯化的鱼。这些结果表明，NHE 3参与肾Na（+）重吸收，尿酸化，肠Na（+）吸收的板鳃类。
Na(+)/H(+) exchanger 3 (NHE3) provides one of the major Na(+) absorptive pathways of the intestine and kidney in mammals, and recent studies of aquatic vertebrates (teleosts and elasmobranchs) have demonstrated that NHE3 is expressed in the gill and plays important roles in ion and acid-base regulation. To understand the role of NHE3 in elasmobranch osmoregulatory organs, we analyzed renal and intestinal expressions and localizations of NHE3 in a marine elasmobranch, Japanese banded houndshark (Triakis scyllium). mRNA for Triakis NHE3 was most highly expressed in the gill, kidney, spiral intestine, and rectum. The kidney and intestine expressed a transcriptional isoform of NHE3 (NHE3k/i), which has a different amino terminus compared with that of NHE3 isolated from the gill (NHE3g), suggesting that NHE3k/i and NHE3g arise from a single gene by alternative promoter usage. Immunohistochemical analyses of the Triakis kidney demonstrated that NHE3k/i is expressed in the apical membrane of a part of the proximal and late distal tubules in the sinus zone. In the bundle zone of the kidney, NHE3k/i was expressed in the apical membrane of the early distal tubules known as the diluting segment. In the spiral intestine and rectum, NHE3k/i was localized toward the apical membrane of the epithelial cells. The transcriptional levels of NHE3k/i were increased in the kidney when Triakis was acclimated in 130% seawater, whereas those in the spiral intestine were increased in fish acclimated in diluted seawater. These results suggest that NHE3 is involved in renal Na(+) reabsorption, urine acidification, and intestinal Na(+) absorption in elasmobranchs.