Localization of ammonia transporter Rhcg 1 in mitochondrion-rich cells of yolk sac, gill, and kidney of zebrafish and its ionic strength-dependent expression
Localization of ammonia transporter Rhcg 1 in mitochondrion-rich cells of yolk sac, gill, and kidney of zebrafish and its ionic strength-dependent expression
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DOI：
10.1152/ajpregu.00248.2007
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发表时间：
2007-10-01
影响因子：
2.8
通讯作者：
Hirose, Shigehisa
中科院分区：
文献类型：
--
作者：
Nakada, Tsutonm;Hoshijima, Kazuyuki;Hirose, Shigehisa
Rh糖蛋白家族的成员已被证明参与多种物种的氨转运。在这里，我们表明，斑马鱼Rhcgl，Rh糖蛋白家族的成员，是高度表达的卵黄囊，鳃，肾小管。分子克隆和表征表明，斑马鱼Rhcg 1股82%的序列同一性与河豚的直系同源fRhcg 1。RT-PCR结合原位杂交结果显示，RhcgI在受精后3天（dpf）的卵黄囊上首先表达于液泡型H+-ATP酶/富含钙离子的细胞（vH-MRC），随后在4-5 dpf的鳃中表达于vH-MRC样细胞。斑马鱼幼虫的氨排泄量与Rhcgl的表达平行增加。在幼虫阶段，RhcgI mRNA检测到只有卵黄囊和鳃，然而，肾脏，以及鳃，成为一个主要网站的RhcgI在成人的表达。使用其vH-MRC用绿色荧光蛋白（GFP）和针对斑马鱼Rhcgl的抗体标记的斑马鱼Tol 2转基因系，我们证明RhcgI位于1）卵黄囊上的vH-MRC和vH-MRC样细胞的顶端区域（具有RhcgI和GFP表达的细胞群）和2）肾远端小管和闰细胞中的细胞-就像肾脏集合管中的细胞一样值得注意的是，Rhcgl mRNA的表达在幼虫阶段的环境离子强度的变化。这些结果表明，斑马鱼Rhcgl的作用不仅仅是分泌氨，以消除氮从鳃。
Members of the Rh glycoprotein family have been shown to be involved in ammonia transport in a variety of species. Here we show that zebrafish Rhcgl, a member of the Rh glycoprotein family, is highly expressed in the yolk sac, gill, and renal tubules. Molecular cloning and characterization indicate that zebrafish Rhcg1 shares 82% sequence identity with the pufferfish ortholog fRhcg1. RT-PCR, combined with in situ hybridization, revealed that RhcgI is first expressed in vacuolar-type H+-ATPase/ mitochondrion-rich cells (vH-MRC) on the yolk sac of larvae at 3 days postfertilization (dpf) and later in vH-MRC-like cells in the gill at 4-5 dpf. Ammonia excretion from zebrafish larvae increased in parallel with the expression of Rhcgl. At larval stages, RhcgI mRNA was detected only on the yolk sac and gill; however, the kidney, as well as the gill, becomes a major site of RhcgI expression in adults. Using a zebratish Tol2 transgenic line whose vH-MRC are labeled with green fluorescent protein (GFP) and an antibody against zebrafish Rhcgl, we demonstrate that RhcgI is located in the apical regions of 1) vH-MRC on the yolk sac and vH-MRC-like cells (cell population with the expression of RhcgI and GFP) in the gill and 2) cells in the renal distal tubule and intercalated cell-like cells in the collecting duct of the kidney. Remarkably, expression of Rhcgl mRNA at the larval stage was changed by environmental ionic strength. These results suggest that roles of zebrafish Rhcgl are not solely ammonia secretion to eliminate nitrogen from the gill.