Aquaporin 2 is a vasopressin-independent, constitutive apical membrane protein in rat vas deferens.
Aquaporin 2 is a vasopressin-independent, constitutive apical membrane protein in rat vas deferens.
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DOI：
10.1152/ajpcell.2000.278.4.c791
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发表时间：
2000-04
期刊：
影响因子：
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通讯作者：
A. L. Stevens;S. Breton;C. Gustafson;R. Bouley;R. Nelson;D. Kohan;D. Brown
中科院分区：
文献类型：
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作者：
A. L. Stevens;S. Breton;C. Gustafson;R. Bouley;R. Nelson;D. Kohan;D. Brown
水通道蛋白2（AQP 2），加压素调节的水通道，最初被确定在肾集合管主细胞。然而，我们最近对输精管中AQP 2的描述表明，该水通道可能具有肾外功能，可能与男性生殖道中的精子浓度有关。在本研究中，我们研究了AQP 2在输精管中的调节和膜插入途径。输精管AQP 2的氨基酸序列与肾蛋白的氨基酸序列具有100%的同源性。AQP 2在输精管的远端部分（壶腹）高度表达，但在最接近附睾的近端部分不表达。它主要集中在输精管主细胞的顶端质膜上，在细胞内小泡上检测到很少。蛋白质表达水平和细胞定位模式在正常大鼠和加压素缺乏的Brattleboro纯合子大鼠中相似，并且在脱水36小时后或加压素输注到Brattleboro大鼠3天后没有改变。在输精管主细胞的顶端内体（用德克萨斯红-葡聚糖标记）中未发现AQP 2，表明其在该组织中不快速再循环。最后，用[3 H]加压素结合试验在输精管上皮细胞膜上检测不到加压素受体。这些数据表明，AQP 2是一个组成性顶膜蛋白在输精管，它不是加压素调节在这个组织。因此，AQP 2包含靶向信息，可以在体内以细胞类型特异性方式解释。
Aquaporin 2 (AQP2), the vasopressin-regulated water channel, was originally identified in renal collecting duct principal cells. However, our recent description of AQP2 in the vas deferens indicated that this water channel may have extra-renal functions, possibly related to sperm concentration in the male reproductive tract. In this study, we have examined the regulation and membrane insertion pathway of AQP2 in the vas deferens. The amino acid sequence of vas deferens AQP2 showed 100% identity to the renal protein. AQP2 was highly expressed in the distal portion (ampulla) of the vas deferens, but not in the proximal portion nearest the epididymis. It was concentrated on the apical plasma membrane of vas deferens principal cells, and very little was detected on intracellular vesicles. Protein expression levels and cellular localization patterns were similar in normal rats and vasopressin-deficient Brattleboro homozygous rats, and were not changed after 36 h of dehydration, or after 3 days of vasopressin infusion into Brattleboro rats. AQP2 was not found in apical endosomes (labeled with Texas Red-dextran) in vas deferens principal cells, indicating that it is not rapidly recycling in this tissue. Finally, vasopressin receptors were not detectable on vas deferens epithelial cell membranes using a [(3)H]vasopressin binding assay. These data indicate that AQP2 is a constitutive apical membrane protein in the vas deferens, and that it is not vasopressin-regulated in this tissue. Thus AQP2 contains targeting information that can be interpreted in a cell-type-specific fashion in vivo.