Cloning and characterization of the urea transporter UT3 - Localization in rat kidney and testis
Cloning and characterization of the urea transporter UT3 - Localization in rat kidney and testis
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DOI：
10.1172/jci119313
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发表时间：
1997-04-01
影响因子：
15.9
通讯作者：
Hediger, MA
中科院分区：
文献类型：
--
作者：
Tsukaguchi, H;Shayakul, C;Hediger, MA
肾脏中的尿素转运对尿浓缩和氮平衡起着重要作用。最近，克隆了三种类型的尿素转运蛋白，分别是来自大鼠和兔肾的UT1和UT2以及来自人骨髓的HUT11。为了阐明后者尿素转运蛋白的生理作用，我们分离了HUT11的大鼠同源物（UT3）并研究了其表达分布和功能特征。 UT3 cDNA编码一个384个氨基酸残基的蛋白质，与人HUT11有80%的同一性，与大鼠UT2有62%的同一性。与注射水的卵母细胞相比，非洲爪蟾卵母细胞中的功能表达导致尿素的吸收大幅增加（大约50倍）。根皮素 (0.75 mM) 和 pCMBS (0.5 mM) 抑制摄取（分别抑制 55% 和 32%）。 Northern分析在肾脏内外髓质、睾丸、脑、骨髓、脾脏、胸腺和肺中显示出3.8 kb的单条带，大鼠肾脏原位杂交显示UT3 mRNA在外髓质内条带、内髓质、乳头表面上皮和泌尿道移行尿上皮中表达。使用针对 van Willebrand 因子的抗体进行的共染色实验表明，外髓质内条纹中的 UT3 mRNA 在降血管直肠中表达。这些数据表明肾脏中的UT3参与升、降血管直肠之间的逆流交换，以增强皮质乳头渗透压梯度。睾丸原位杂交显示UT3位于生精小管的支持细胞中。该信号仅在与精母细胞发育早期阶段相关的支持细胞中检测到，表明尿素可能在精子发生中发挥作用。
Urea transport in the kidney plays an important role in urinary concentration and nitrogen balance. Recently, three types of urea transporters have been cloned, UT1 and UT2 from rat and rabbit kidney and HUT11 from human bone marrow, To elucidate the physiological role of the latter urea transporter, we have isolated the rat homologue (UT3) of HUT11 and studied its distribution of expression and functional characteristics. UT3 cDNA encodes a 384 amino acid residue protein, which has 80% identity to the human HUT11 and 62% identity to rat UT2. Functional expression in Xenopus oocytes induced a large (similar to 50-fold) increase in the uptake of urea compared with water-injected oocytes. The uptake was inhibited by phloretin (0.75 mM) and pCMBS (0.5 mM) (55 and 32% inhibition, respectively). Northern analysis gave a single band of 3.8 kb in kidney inner and outer medulla, testis, brain, bone marrow, spleen, thymus, and lung, In situ hybridization of rat kidney revealed that UT3 mRNA is expressed in the inner stripe of the outer medulla, inner medulla, the papillary surface epithelium, and the transitional urinary epithelium of urinary tracts. Co-staining experiments using antibody against van Willebrand factor showed that UT3 mRNA in the inner stripe of the outer medulla is expressed in descending vasa recta. These data suggest that UT3 in kidney is involved in counter current exchange between ascending and descending vasa recta, to enhance the cortico-papillary osmolality gradient, In situ hybridization of testis revealed that UT3 is located in Sertoli cells of seminiferous tubules. The signal was only detected in Sertoli cells associated with the early stages of spermatocyte development, suggesting that urea may play a role in spermatogenesis.